Para-aortic blood pump device

ABSTRACT

A para-aortic blood pump device includes a blood pump, an aortic adapter, a driveline, and a driver. The blood pump includes a blood sac, a pump housing and a pressure sensor, whereas the pressure sensor is installed in the pump housing for monitoring the blood pressure inside the blood pump. The aortic adapter is a T-manifold shaped conduit connected to the blood pump and is used for connecting the blood pump with human aorta to facilitate circulatory support. The driveline allows a pneumatic communication to the blood pump in addition to transmitting the electrical blood pressure signal to the driver. The driver receives and processes the electrical blood pressure signal, decides the timing, speed and duration of blood pump fill and eject actions so as to provide counter-pulsatile circulatory support to assist human circulation.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.63/162,086 and No. 63/162,098 filed on Mar. 17, 2021, the entirety ofwhich is incorporated by reference herein.

BACKGROUND OF INVENTION Field of the Invention

The present invention relates to a ventricular assist device (VAD), inparticular to a left ventricular assist device (LVAD) based on theprinciple of counterpulsation support.

Description of the Related Art

Mechanical Circulatory Support in Heart Failure Treatment

The disease progression of heart failure is characterized by a viciouscycle. Medical therapy for early-to-moderate stage heart failure is tosuppress the neurohormonal compensatory mechanism, which slows downrather than remedies the death spiral of the heart failure viscouscycle. Heart transplant or ventricular assist device (VAD) implantationis intended to be used for the terminal-stage heart failure. Thereexists an “unmet need” gap region between the medically ineffective andtransplant/VAD treatments along the course of heart failure progression.As heart failure deteriorates beyond effective medical treatment stage,often, patients cannot receive any therapy but waiting for heart failureto deteriorate further into the refractory stage where transplant/VADcan be considered. This treatment gap is categorized as InteragencyRegistry for Mechanical Assisted Circulatory Support (INTERMACS)profiles 4-7, and patients in this class of heart failure typically showsymptoms of apnea, pulmonary hypertension, renal hypoperfusion andexercise intolerance with elevated inflammatory responses.

The best policy for treating heart failure by mechanical circulatorysupport (MCS) is to implant a left ventricular assist device (LVAD) intime before a failing heart becomes refractory. However, this policy isnot practically realizable because the current rotary pumps, orcontinuous-flow LVADs, are invasive in implantation and involve withconsiderable post-operative morbidity rates, making the LVADs onlyindicated for terminal-stage heart failure patients.

Counter-pulsatile support therapeutics has been clinically proveneffective for more than fifty years by the bedside intra-aortic balloonpump (IABP) administration. The recent success in extending IABP usefrom bedside to ambulatory support, via implanting the balloon pump fromaxillary or subclavian artery, has achieved bridging patients to hearttransplant. Balloon counterpulsation together with patient ambulationshowed surprisingly good benefit in improving the heart functionalstatus. Nevertheless, this balloon delivery site improvement is only atemporary solution. Patients treated by ambulatory IABP are stillbounded in hospital and the axillary or subclavian insertion cannot beused safely in a long-term period.

Currently, there exist no clinically approved partial-support (bloodpump providing 2-3 Liter per minute pump flow), early interventiondevices that are specifically indicated for less-sick advanced heartfailure patients. A great portion of such less-sick heart failurepatients will deteriorate and develop acute myocardial ischemia orcardiogenic shock requiring emergent mechanical circulatory support. Thelife-sustaining, acute circulatory support systems such as IABP,extracorporeal membrane oxygenation (ECMO), and percutaneous micro-axialcatheter pumps could be emergently administered, however, the mortalityrate of the supported patients is generally high in the range of 40-70%.Moreover, it is often difficult for patients, families, and cliniciansto decide if invasive and expensive rotary pumps should be used afterthe exhaustion of the acute circulatory support devices. Therefore, itis a main subject for related manufacturers to overcome the therapeuticgap in heart failure treatment, by innovating new long-term implantableVAD design that encompasses the early intervention and less traumaticsurgery concept.

Early Intervention Partial-Support LVAD

An early intervention partial-support blood pump, also known as apara-aortic blood pump device, was presently invented according to thecounterpulsation support principle. The para-aortic blood pump device ofthe present invention provides a counter-pulsatile circulatory supportincluding augmentation of systemic blood flow during diastole (heartrelaxation) to improve myocardial and organ perfusion while reducingleft ventricular workload during systole (heart contraction). Formechanical circulatory support device recipients, earlier hemodynamicsupport and post-operative ambulatory ability is important for survivaland disease improvement. Less invasive surgery, a premise of earlyintervention, hence, constitutes another critical element aside from thehemodynamic therapeutics the partial-support LVADs can provide. With theaid of specially designed surgical tools, the para-aortic blood pumpdevice of the present invention can be safely implanted via a lesstraumatic surgical procedure (such as a beating-heart mini-leftthoracotomy). Evidences gathered from several contemporary clinicaltrials performed for late-stage heart failure patients have shown thatchronic LVAD-supported heart, either by displacement type blood pump orby rotary pump, can encourage the nonischemic myocardium undergocellular reverse remodeling, resulting in a significant portion ofdevice-treated patients gaining robust myocardial recovery or remission.This finding implies that if early ambulatory support feature can beincluded in LVAD design and instituted in treating heart failure, themechanical unloading would be potentially more effective and beneficialfor salvaging the less-sick (INTERMACS profiles 4-7) patients.

It is plausible and beneficial that before heart transplant orimplanting highly invasive rotary pumps, patients can be treated by theless traumatic para-aortic blood pump device for an extended period.Some patients may recover with the circulatory assistance offered by thepara-aortic blood pump device, executed via therapeutic counterpulsationfor months or longer (1-2 years) in the form of ambulatory support. Forthose hemodynamically stabilized but non-recoverable recipients, thepara-aortic blood pump device can be used in a long-term manner as adestination therapy device or as a bridging to transplant. Thepara-aortic blood pump device, hence, can serve as an interim salvagemodality before heart transplant or an expensive and invasive rotarypump implantation. The role of the para-aortic blood pump device inheart failure treatment is multi-faceted, it can be used as a means forbridge-to-recovery (or remission), bridge-to-decision (rotary pump),bridge-to-transplant, or alternative-to-transplant (destinationtherapy).

BRIEF SUMMARY OF INVENTION

It is one of primary objectives of the present invention to overcome theshortcomings of the prior art by disclosing a para-aortic blood pumpdevice comprising: a blood pump, an aortic adapter, a driveline, and adriver. The blood pump comprises a pump housing, a blood sac, and apressure sensor, and the pressure sensor is installed in the pumphousing of the blood pump for monitoring blood pressure inside the bloodpump. The sensed blood pressure is transduced into an electrical signalto be transmitted through a driveline into a driver. The aortic adapteris a T-manifold shaped flow conduit coupled to the blood pump and usedfor integrating the blood pump with the human aorta. The aortic adapteris thin-walled and may have structural reinforcement embedded forstrength enhancement. The driveline is coupled to the housing of theblood pump, providing a pneumatic communication to the blood pump andtransmitting the electrical blood pressure signal received from thepressure sensor. The driver is coupled to the driveline for receivingthe electrical blood pressure signal. The driver comprises anelectro-mechanical actuator commanded by a controller in the driver togenerate counter-pulsatile pneumatic pressure pulse according to thesensed electrical blood pressure signal. The pressure pulse is sent toand from the blood pump through the driveline, fulfilling the ejectionand filling action of the blood pump when supporting the humancirculation.

In some embodiments, the driver further comprises a driveline controllerand a vibrator, and the driveline controller is used for processing theelectrical blood pressure signal, and the vibrator is used for providingan audible alarm or a tactile feedback.

In some embodiments, the driveline and a part of the driver aresubstituted by a distal driveline, a driveline interconnector and aproximal driveline, and the distal driveline is provided fortransmitting the electrical blood pressure signal and the pressure pulseto the blood pump, and the driveline interconnector comprises adriveline controller and a vibrator, and the driveline controller isused for processing the electrical blood pressure signal, and thevibrator is used for providing an audible alarm or a tactile feedback.

In some embodiments, the blood pump and the aortic adapter areintegrally formed.

In some embodiments, the para-aortic blood pump device comprises acoupler, and the coupler includes a coupling adapter installed at a neckof the aortic adapter for coupling the blood pump to the aortic adapter.

In some embodiments, two gradually flared ends of the aortic adapterconstitute a smooth transition of an elastic property, beingprogressively softer in proportion to a wall thickness toward the end.

In some embodiments, the pump housing of the blood pump is installedwith the blood sac therein, and the blood sac is an oval-shaped membranebody of revolution to a centerline of the blood pump, at two ends thereare two polymeric stems that are bonded with the membrane body, workingas a flexing/stretching relief mechanism to alleviate stressconcentration when attached onto the pump housing of the blood pump.

In some embodiments, the pump housing of the blood pump has an opening,and the opening continuously integrates with the aortic adapter thatprovides a smooth interface with a neck of the aortic adapter.

In some embodiments, the electro-mechanical actuator comprises apressure equalization valve connected to an air chamber, and thepressure equalization valve is opened periodically so that an airpressure in the air chamber can be set to be in equilibrium withatmospheric pressure.

In some embodiments, the para-aortic blood pump device provides acounter-pulsatile augmentation of systemic blood flow during diastole(heart relaxation) to improve myocardial and organ perfusion whilereducing left ventricular workload during systole (heart contraction).

In some embodiments, the driver further comprises a trigger-detectionmicro controller unit, and the electrical blood pressure signal providesthe sensed pressure waveform within the blood pump for thetrigger-detection micro controller unit to compute and determine theeject and fill timings for the electro-mechanical actuator.

In some embodiments, the electro-mechanical actuator comprises a motorand ball screw/nut unit that drives a reciprocating piston within acylinder of electro-mechanical actuator; the movement of the pistonpushes and withdraws air via the driveline coupled to the blood pump.

In some embodiments, wherein the electro-mechanical actuator is apneumatic actuator includes: a brushless servo motor and a ball screwpiston/cylinder assembly, wherein atmospheric air is used as a drivingmedium to reciprocally eject/fill the blood pump; and a pressureequalization valve is equipped on the electro-mechanical actuator tosolve the problems of air leakage at a piston ring and condensation ofvapor permeated out from a blood sac membrane.

In some embodiments, the driver receives the electrical blood pressuresignal and processes the electrical blood pressure signal using triggerdetection algorithm to generate a trigger signal that commands a driveractuation in synchronization with heart rhythm.

In some embodiments, upon receiving the assigned trigger timing, themicro controller unit sends commands to a motor controller to drive apiston of the electro-mechanical actuator, from eject-to-fill or fromfill-to-eject positions, to provide counter-pulsatile circulatorysupport including contraction unloading during the cardiac systolicphase and perfusion augmentation during the cardiac diastolic phase,respectively.

In some embodiments, the driver further comprises a user interface, andthe user interface comprises an indicator, an audio alarm, a button anda liquid crystal display (LCD).

In some embodiments, when the micro controller unit loses the electricalblood pressure signal from the blood pump, a washout mode is launchedautomatically by the micro controller unit to drive theelectro-mechanical actuator, operating at a predetermined pumping rateand driver stroke volume.

In some embodiments, the washout mode is used to prevent the formationof thrombus in the blood pump, which is a device protection mode insteadof providing circulatory support.

In some embodiments, the blood sac is anchored via a proximal stem to aproximal shell of the pump housing and via a distal stem to a distalshell of the pump housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a para-aortic blood pump device inaccordance with a first embodiment of the present invention;

FIG. 2 is a schematic view of a para-aortic blood pump device inaccordance with a second embodiment of the present invention;

FIG. 3 is a schematic view of a para-aortic blood pump device inaccordance with a third embodiment of the present invention;

FIG. 4 is a schematic view of a para-aortic blood pump device inaccordance with a fourth embodiment of the present invention;

FIG. 5 is a schematic view of a para-aortic blood pump device installedin human body in accordance with the first and second embodiments of thepresent invention;

FIG. 6 is a schematic view of a para-aortic blood pump device installedin human body in accordance with the third and fourth embodiments of thepresent invention;

FIG. 7 is a first schematic view of a driver in accordance with anexemplary embodiment of the present invention;

FIG. 8 is a second schematic view of a driver in accordance with anexemplary embodiment of the present invention;

FIG. 9 is a block diagram of the driver functions and the keyinterconnecting signals that are necessary for the operation of thepresent invention;

FIG. 10 is a block diagram of the driver functions and the keyinterconnecting signals that are necessary for the operation of thethird embodiment of the present invention;

FIG. 11 is a block diagram of the driver functions and the keyinterconnecting signals that are necessary for the operation of thesecond embodiment of the present invention;

FIG. 12 depicts the trigger-detection commands for electro-mechanicalactuator (EMA) piston position in relation to the counter-pulsatilepumping;

FIG. 13A is a perspective view showing a para-aortic blood pump implantin accordance with the first or third embodiment of the presentinvention;

FIG. 13B is a sectional view showing a para-aortic blood pump implant inaccordance with the first or third embodiment of the present invention;

FIG. 14A is a perspective view showing a para-aortic blood pump implantin accordance with the second or fourth embodiment of the presentinvention;

FIG. 14B is a sectional view showing a para-aortic blood pump implant inaccordance with the second or fourth embodiment of the presentinvention;

FIG. 15 shows the driveline connection to the pump housing of the bloodpump being accomplished via a feedthrough on the distal shell accordingto another embodiment of the present invention;

FIG. 16 shows a sectional view of the blood pump illustrated in FIG. 15;

FIG. 17 shows a superficial trench design for extending the electricwires from the feedthrough disposed in the distal shell to the pressuresensing chamber in the proximal shell;

FIG. 18A shows a surgical end-to-side anastomosis of the present bloodpump invention to an artery via the use of an interface adaptercoupling;

FIG. 18B shows coupling of the present blood pump to an artery via aninsertion type connection method using a T-shaped endovascular connectorcoupled by an interface adapter;

FIG. 19 illustrates a sectional view of the body of revolution of anintegrated axi-symmetric oval-shaped blood sac and stem assemblyincluding a sac, a proximal stem and a distal stem;

FIG. 20 is an exploded view showing the components used for theconstruction of the axi-symmetric oval-shaped blood sac and stemassembly (Note that the sac is in its original shape before bondingintegration to the proximal and distal stems illustrated in FIG. 19);

FIG. 21 illustrates the buckled tri-lobe sac configuration (eigenmode)at the end of ejection of the blood sac illustrated in FIG. 19;

FIG. 22 depicts a perspective view of the driveline connected to theproximal shell of the blood pump via the feedthrough;

FIG. 23A illustrates a sectional view of the blood pump and distalportion of the driveline taken along the section A-A in FIG. 6;

FIG. 23B shows a sectional view of the proximal end of the drivelinetaken along the section A-A in FIG. 22;

FIG. 24 shows a sectional view of a de-airing port installed in theproximal shell corresponding to the first embodiment;

FIG. 25A shows a sectional view of a pressure sensing chamber and afeedthrough in the proximal shell of the first embodiment. Note that thedriveline is not mounted and the feedthrough comprises a first portion,an extension of the proximal shell, and a second portion that isinterlocked with the first portion;

FIG. 25B shows a perspective view of a micro electro-mechanical system(MEMS) pressure sensor incorporated in FIG. 25A;

FIG. 26 shows a perspective view of a multi-layered driveline of thepresent invention, in which inner tubing for pneumatic air transport,middle tubing for electric signal transduction as well as coils, tethersand outer tubing are included;

FIG. 27 shows a cross-sectional view of a multi-luminal driveline designoption of the driveline;

FIG. 28A shows a typical view of flow characteristics in the pumpfilling phase;

FIG. 28B shows a typical view of flow characteristics in the pumpejection phase;

FIG. 29 is a perspective view of the present embodiment of the T-shapedaortic adapter;

FIG. 30 is a sectional view of the present embodiment of the T-shapedaortic adapter;

FIG. 31 is an expanded two-dimensional illustration of the embeddedNitinol truss;

FIG. 32 defines the lateral stiffness (LS) used in the measurement ofNitinol truss embedded conduit of the T-shaped aortic adapter;

FIG. 33 shows an exploded view of the parts included in the coupler;

FIG. 34A shows an integrated view of coupler in the open configuration;

FIG. 34B shows an integrated view of coupler in the latchedconfiguration;

FIG. 35 is a sectional view of the aortic adapter integrated with apara-aortic blood pump using the coupler;

FIG. 36A depicts a step discontinuity generated by butt joint method;

FIG. 36B depicts a gap discontinuity generated by butt joint method;

FIG. 37 shows a perspective view of an inlet adapter to be installed atthe distal end of a para-aortic blood pump;

FIG. 38 shows a sectional view of an inlet adapter to be installed atthe distal end of a para-aortic blood pump;

FIG. 39 shows a sunk beak of the inlet adapter as connected with theramp surface at the neck of the T-shaped aortic adapter;

FIG. 40 depicts a perspective view of a crimped aortic adapter as packedinto a delivery configuration by string constraints;

FIG. 41A depicts a packed aortic adapter being inserted half-way acrossan access hole made in the aortic wall;

FIG. 41B depicts a packed aortic adapter inserted fully into aorticlumen;

FIG. 41C depicts a packed aortic adapter repositioned with its T-neckfacing the aortic access hole;

FIG. 41D depicts an expanded, deployed aortic adapter with its T-neckpopped out of the aortic access hole after string release; and

FIG. 42 describes the step-by-step instruction of implanting the aorticadapter into a targeted aortic segment and the connection with a bloodpump.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

There are four embodiments that can be employed to realize the presentpara-aortic blood pump invention, as described below.

With reference to FIG. 1 for the schematic view of a para-aortic bloodpump device in accordance with the first embodiment of the presentinvention, the para-aortic blood pump device 10 comprises: a blood pump12, an aortic adapter 14, a driveline 16 and a driver 18. The blood pump12 further comprises a pump housing and a pressure sensor. The bloodpump housing consists of two chambers, one for blood storage and anotherto receive driving air. These two chambers are separated by anoval-shaped flexible membrane suspended via a pair of stress-reliefstems attached to the pump housing. The pressure sensor is installed inthe pump housing for monitoring blood pressure inside the blood pump 12to generate electrical blood pressure signal. The aortic adapter 14 is avalveless, T-manifold shaped flow communicator coupled with the bloodpump 12 and human aorta. In the first embodiment, the aortic adapter 14and the blood pump 12 are integrally formed, having a seamless bloodcontacting surface, and the aortic adapter 14 is provided for connectingthe blood pump 12 with the human aorta. The aortic adapter 14 is made offlexible materials, allowing the aortic adapter 14 be deformed duringinsertion delivery from a hole made on the aortic wall. This aorticadapter conduit, after inserted, is self-expandable and strong enough towithhold the radial compression exerted from oversized fitting to thecontacted aortic lumen. The driveline 16 is coupled to the pump housingof the blood pump 12 for providing a pressure pulse to the blood pump 12and transmitting the electrical blood pressure signal received from thepressure sensor. The driver 18 is coupled to the driveline 16 forreceiving the sensed electrical blood pressure signal, and the driver 18comprises an electro-mechanical actuator to generate a pressure pulseaccording to the electrical blood pressure signal and provides aregulated pressure pulse to the blood pump 12 through the driveline 16.The wearable driver 18 provides timed air pressure pulses insynchronization to cardiac rhythm to drive and control the eject andfill of the implanted blood pump 12.

The driver 18 comprises a battery power system 11 and a redundantbattery power system (the battery power systems 21, 31, 41 in the FIGS.2-4, and 8 are the same or similar), wherein the redundant battery powersystem ensures a continuous power supply of the driver 18. Power canalso be supplied to the driver 18 by an AC adapter for the convenienceof the device recipient when mobility is not required. Further, aclinical monitor unit, not shown in FIGS. 2-4, can be connected to thedriver 18 to provide a user interface to the clinician for displayingdevice monitoring or diagnostic information and for accessing to driverparameters in order to initiate and optimize a patient-specificoperational mode setting.

In FIGS. 1 and 2 illustrated two different blood pump 12, 22 designscoupled with the same driveline 16, 26 and driver 18, 28 system. FIG. 2is the schematic view of a para-aortic blood pump device 20 inaccordance with the second embodiment of the present invention, and thedifference between the second embodiment and the first embodiment of thepresent invention resides on that the para-aortic blood pump device 20of the second embodiment further comprises a coupler (or couplingadapter) 25. The blood pump 22 and the aortic adapter 24 of the secondembodiment are not integrally formed, but are detachable from eachother; and the coupler 25 is provided for coupling the blood pump 22 tothe aortic adapter 24. Care must be exercised in the coupler design tominimize the interface discontinuity around the connected region. Duringdevice implantation, the aortic adapter 24 is first inserted into theaorta via an access hole made in the aortic wall. Using speciallydeveloped implantation tools, a coupling adapter 25 is disposed aroundthe protruded neck of the aortic adapter 24, to which the blood pump 22can be connected. Following the introduction of the blood pump 22 intothe thoracic cavity, the blood pump 22 and the aortic adapter 24 arefirmly integrated using the coupler 25. Such detachable blood pump 22and aortic adapter 24 design encompasses surgical and post-operativeadvantages. During device implantation, the detachable pump designrenders the aortic adapter insertion easier because the surgical fieldis clearer without the interference of the pump body. Further, in thepost-operative period, blood pump can be detached and exchanged in caseof pressure sensor malfunction or blood sac rupture requiring emergentsurgical replacement. The detachable blood pump design of the secondembodiment is advantageous in this regard. The aortic adapter can stayin the aorta without explantation, avoiding troublesome and risky redosurgery associated with aortic adapter removal.

With reference to FIGS. 1 and 3 for the schematic views of thepara-aortic blood pump devices 10, 30 in accordance with the first andthe third embodiment of the present invention respectively, thedifference between the third embodiment and the first embodiment of thepresent invention resides on that the driveline 16 of the firstembodiment are substituted by the driveline 36 including the distaldriveline 37, the driveline interconnector 33 and the proximal driveline39 of the third embodiment. The distal driveline 37 is coupled to thedriveline interconnector 33 for transmitting the electrical bloodpressure signal acquired from the pressure sensor and the pressure pulsesent from the driver 38; and the driveline controller and the vibrator(for alarm warning purpose) included in the driveline interconnector 33are originally included in the driver 18 of the first embodiment, sothat the driver 18 of the first embodiment has the additional drivelinecontroller and vibrator (compared with the driver 38 of the thirdembodiment). The driveline controller is used for processing theelectrical blood pressure signal, and the vibrator is used for providingan audible alarm or a tactile feedback. In other words, the mechanicalpower transmission to fill and eject the blood pump and theanalog/digital signal conversion and alarm annunciation, achievedrespectively by the driveline 16 and the driver 18 of the firstembodiment, are substantially the same as those by the distal driveline37, the driveline interconnector 33 and the proximal driveline 39 of thethird embodiment.

The first embodiment has a cleaner driveline configuration and disposeselectronic signal processor in the driver, hence minimizing the risk ofenvironmental contamination (water ingress or moisture condensation) ofthe sensed pressure signal and the air leak incurred at the joint, bothassociated with the driveline interconnector 33. Nevertheless, this longdriveline is more vulnerable to contact damage such as wear, kink, cut,abrasion arising from the contact with foreign objects in dailyactivities. Any major damage to the driveline 16 of the first or secondembodiment, either electronically or mechanically, may warrant surgicalblood pump replacement that is highly undesirable in view of surgicalredo risk and the associated medical costs. The third or fourthembodiment, by employing a mid-way connector (driveline interconnector),mitigates such driveline damage-related blood pump replacement drawback.In general, the length of externalized distal driveline 37 is short andthe interconnector 33 is protected better by the coverage of the skindressing and/or the patient vest. In the extreme case of severe damageof the driveline beyond repairable, the most possibly damaged proximaldriveline 39 can be easily exchanged without resorting to surgery. Inaddition, the third or fourth embodiment is more immune toelectromagnetic interference because the analog-to-digital signalconversion is already accomplished in the circuitry in theinterconnector 33. The fidelity of pressure signals can be betterassured in the third or fourth embodiment because digital signaltransmission in the proximal driveline 39 is less susceptible to theelectromagnetic interferences.

With reference to FIGS. 3 and 4 for the schematic views of thepara-aortic blood pump device 30, 40 in accordance with the third andthe fourth embodiment of the present invention respectively, thedifference between the third embodiment and the fourth embodimentresides on that the aortic adapter 34 and the blood pump 32 of the thirdembodiment are integrally formed; whereas the blood pump 42 and theaortic adapter 44 of the fourth embodiment are detachable; and thefourth embodiment further comprises a blood pump 42, an aortic adapter44 and a coupler 45 which are the same as the blood pump 22, the aorticadapter 24, and the coupler 25 of the second embodiment, and thus theirdescriptions will not be repeated. The driveline 46 including the distaldriveline 47, the driveline interconnector 43 and the proximal driveline49 of the fourth embodiment is the same as the driveline 36 includingthe distal driveline 37, the driveline interconnector 33 and theproximal driveline 39 of the third embodiment.

With reference to FIG. 5 for the schematic view of a para-aortic bloodpump device installed in human body in accordance with an exemplaryembodiment of the present invention, the para-aortic blood pump device90 comprises a blood pump 92, an aortic adapter 94, an internaldriveline 991, an external driveline 993, and a driver 98. In anotherembodiment, the para-aortic blood pump device further comprises acoupler. The part of the para-aortic blood pump device 90 implanted intothe human body includes the blood pump 92, the aortic adapter 94 and theinternal driveline 991. In another embodiment, the para-aortic bloodpump further comprises a coupler. After a surgical operation, the aorticadapter 94 is installed into an aorta 95, and an exit site EX is createdat an appropriate position of an epidermis of the human body. The partof the para-aortic blood pump device 90 situated outside the human bodyincludes the external driveline 993, and the driver 98. The exit site EXis used as a boundary, and the internal driveline 991 has a segmentcovered by a fabric velour for tissue ingrowth to attain infectioncontrol. The implanted velour portion is placed 2-5 cm subcutaneouslyfrom the exit site EX. The driver 98 is a wearable or portable device.

With reference to FIG. 6 for the schematic view of a para-aortic bloodpump device installed to human body in accordance with an exemplaryembodiment of the present invention, the para-aortic blood pump device90 comprises a blood pump 92, an aortic adapter 94, a distal driveline97 (including an internal distal driveline 971, an external distaldriveline 973 outside the human body), a driveline interconnector 93, aproximal driveline 99 and a driver 98. In another embodiment, thepara-aortic blood pump device 90 further comprises a coupler. The partof the para-aortic blood pump device 90 implanted into the human bodyincludes the blood pump 92, the aortic adapter 94 and the internaldistal driveline 971. In another embodiment, the para-aortic blood pumpdevice further comprises a coupler. After a surgical operation, theaortic adapter 94 is installed into an aorta 95, and an exit site EX iscreated at an appropriate position of an epidermis of the human body.The part of the para-aortic blood pump device 90 situated outside thehuman body includes an external distal driveline 973, a drivelineinterconnector 93, a proximal driveline 99 and a driver 98. The exitsite EX is used as a boundary, and the distal driveline is divided intoan internal distal driveline 971, covered with velour for infectioncontrol, and an external distal driveline 973. The driver 98 is awearable or portable device.

The implant subsystem is described further below.

Implantation is achieved through a relatively small thoracic opening byusing less invasive surgical techniques via a left thoracotomy. Athoracic incision is made, for example, at the 7th intercostal space asthe primary opening to allow placement of the aortic adapter and theblood pump. Two other small incisions are made at the 6th and 8thintercostal spaces, respectively, to introduce proximal and distalaortic cross clamps. The cross-clamped segment of aorta allows aorticadapter be inserted into the implant site through an excess hole made inthe aortic wall. The aortic adapter is flexible and is able to becrimped and constrained into a smaller delivery configuration prior toinsertion. Upon completion of delivery into aorta, the crimped aorticadapter shall be released and restore back to its original form withpredetermined oversize to the implant site lumen diameter. The materialof the aortic adapter hence is important, which shall be flexible butpossessing sufficient radial strength to make the delivered adapterconduit remain circular without wall buckling. Candidate aortic adapterconstruct may include that made by silicone or polyurethane elastomers,or those polymeric constructs reinforced with embedment.

The functional requirements of the aortic adapter of each of theaforementioned embodiments is further described below.

Hemodynamically, the aortic adapter plays a role of flow communicationbetween the blood pump and human systemic circulation. Besides thisrole, the aortic adapter also serves as a mechanical base to hold theblood pump in place when connected to the aortic adapter. The structureof the aortic adapter has to be elastic but kink resistant, and strongenough to withstand the internal blood pressure and the external contactforces, exerted via contact with the surrounding lung tissue ordiaphragm associated with respiratory and thoracic movement.

The aortic adapter 54 is implanted inside the aorta with its two conduitends 545, 645 interfaced with the aortic lumen forming a host/graftboundary in the blood stream (see FIGS. 7B and 8B). In order to minimizethe host/graft interface discontinuity, both morphologically andelastically, the two conduit ends 545, 645 are configured to have agradually flared inner surface profile and a continuously reduced wallthickness distribution. Such a conduit end design minimizes the step atthe interface as well as constitutes a compliance-matching effect forjoining the aortic adapter with the aortic lumen. Thrombus at theinterface can thus be annihilated because the rate of interface clotaggregation is slower than the natural thrombolysis rate provided by theendothelium. In addition, the gradually thinning conduit wall structurerenders the conduit ends 545, 645 softer (compliant) which enables theends expand and contract in concert with the pulsatile blood pressure,constituting a dynamic seal effect to prevent blood from being jammedinto the gap of the joint interface which often is the origin ofthrombus formation.

The driver of each of the aforementioned embodiments is furtherdescribed below.

Illustrated in FIG. 9 and FIG. 10 are the right-side and left-sideperspective views of the driver 78. This compact driver 78 containsinternal modules including an electromechanical actuator (EMA), anelectronic controller, a pair of main battery and reserve battery. Thisdriver 78 also comprises external modules of a user interface panel 73,a battery access door 71, a driveline receptacle 75, an AC receptacle77, and a pair of ventilation windows 79, as depicted in FIGS. 9 and 10.

Critical information in operation and alarm warning of devicemalfunction and aortic pressure conditions will be displayed on the userinterface panel 73 of the driver 78. The primary battery can beexchanged through the battery access door 71 when primary battery poweris exhausted. An electric cable is used to power the driver 78 via aconnection through the AC receptacle 77 when patient is bedridden andpower from wall outlet can be utilized in a long-term manner. Theproximal driveline 99, 993 end is connected to the driver 78 through thedriveline receptacle 75, through which both electric sensor signal andpneumatic pressure pulse are communicated. A pair of ventilation windows79 are installed on the opposite sides of the driver 78 to allow ambientair to flow through the interior of the driver 78 for cooling purpose.

The driver 78 can be coupled externally to a clinical monitor, whereinthe clinical monitor is provided for collecting and displaying real-timeclinical waveform data and stores patient data for long-term conditionmonitoring and diagnosis. Further, a clinical monitor unit provides auser interface to the clinician for displaying devicemonitoring/diagnostic information and for accessing to driver parametersettings in order to initiate and optimize a patient-specificoperational mode.

The EMA is a pneumatic actuator consisting of a brushless servo motor, aball screw unit, a piston and a cylinder assembly. Atmospheric air isused as a driving medium to reciprocally eject and fill the blood pump.

The EMA module is housed within the driver carried by the implantrecipient. The EMA consists of a brushless servo motor, a piston andcylinder assembly and a ball screw unit which comprises a ball screw rodand a nut. The piston is firmly mounted on top of the ball screw rodwhich is in rotational coupling with the nut of the ball screw unit. Theservo motor includes a stator and a rotor and the rotor is integratedwith the nut of the ball screw unit. Through the electromagneticcoupling of the rotor/stator induction, the rotor can be rotated in bothclockwise and counter-clockwise directions, thereby driving the ballscrew rod back-and-forth in a rectilinear manner to result in areciprocating piston stroke motion in a cylinder. The stroke motion ofthe piston drives air to and from the implanted blood pump via adriveline connecting the blood pump and the cylinder.

There are two air driving problems associated with the present EMApneumatic actuator design; namely, the air leak and the condensation ofwater vapor permeated from the blood through the blood sac wall. Theformer will impair the pump eject and fill function and driver powerconsumption leading to degradation of support effectiveness, and thelatter will cause bacteria invasion risk to the driveline interior. Tosolve these two problems, the present EMA incorporates a pressureequalization valve installed in the cylinder chamber wall for airreplenishment and moisture reduction. The pressure equalization valve isopened periodically at a predetermined frequency, allowing air masstransport between the cylinder and the ambient until the air pressure inthe cylinder chamber equals the atmospheric pressure. The EMAincorporates position and optical sensors to acquire referencetrajectory signals for the electronic controller to generate coordinatedcontrol commands to drive the piston stroke motion as well as to operatethe pressure equalization valve. Hence, the timing and frequency forpressure equalization valve to be activated for air exchange can beprogrammed in the controller. With such pressure equalization valveincorporated the driving air medium can be constantly maintained in fulland dry in the pneumatic actuator to guarantee a long-term safe andeffective pumping support of the blood pump.

As illustrated in FIG. 11, a para-aortic blood pump device in accordancewith an embodiment of the present invention is divided into threeportions. The first portion is largely installed inside the human body(which is an implant) with an externalized end to communicate with thesecond portion; and the first portion comprises a blood pump (includinga blood pump pressure sensor), an aortic adapter and distal drivelinesegments disposed inside and outside human body, respectively. Thesecond portion is installed outside the human body and comprises aproximal driveline and a driveline electronics module (or known as adriveline interconnector). The third portion is installed outside thehuman body, which is a driver comprising an electromechanical actuator(EMA), a controller circuit, a main battery, and a reserve battery.

The blood pump pressure sensor is built into the proximal blood pumpshell and immersed in a small pressure sensing chamber filled withsensing medium, allowing a continuous monitoring of the blood pumppressure. A distal driveline is attached to the pump housing andprovides timed air pressure pulses to command ejection and filling ofthe blood sac. The distal and proximal drivelines provide apneumatically driven pressure pulse, generated by the EMA inside thedriver, to the blood pump; and transmits an electrical blood pressuresignal, generated by the pressure blood pump pressure sensor, to thedriver. A driving air path (indicated by a dotted arrow line) and anelectrical signal path (indicated by a solid-line) is illustrated inFIG. 11 to describe the functional relationship among the interactedmodules. The detailed content of the aortic adapter has been describedabove. The controller circuit can include a motor controller unit fordriving the brushless motor and a micro controller unit as a centralprocessor to process the received pressure signal and generate controlcommands for motor controller to actuate piston motion.

With reference to FIGS. 12 and 13, a block diagram of the driverinternal functions and the key interconnecting signals that arenecessary for actuating the blood pump is shown. The raised embodimentsof the present invention are further described, as illustrated in FIGS.12 and 13. In order to explain the driving relationship between theexternal driver and the implant, it is necessary to refer to theaforementioned contents of the blood pump, driveline, distal driveline,proximal driveline, aortic adapter and driveline interconnector.

The driver receives blood pump pressure signal (electric signal) andprocesses the signal using trigger detection algorithm to generatetrigger signal that commands the EMA actuation in synchronization withthe heart rhythm. Upon receiving the assigned trigger timing, the microcontroller unit sends commands to the motor controller unit to drive thepiston, from eject-to-fill or from fill-to-eject courses, to providecounter-pulsatile circulatory support.

The architecture of the electronic controller incorporates threefunctional blocks, namely, a micro controller unit (MCU), a motorcontrol block (motor controller unit), and a power management unit. Thefollowing Table provides descriptive outlines for each functional blockof the driver 78.

Function Name Description Micro Controller The MCU processes the bloodpump pressure and generates a Unit (MCU) 130 trigger that synchronizesthe device pumping with the left ventricle. According to the triggertiming, the MCU sends motor commands to the Motor Controller to drivethe piston from eject-to-fill or from fill-to-eject positions accordingto the treatment management settings. It also manages system datastorage, system condition monitoring and alarms, commands sent fromClinical Monitor, and patient user interface (LCD display, LEDindicators, and audible alarms). Motor Controller Motor Controller Unit,a motor servo control system that responds Unit 120 to serial commandsfrom MCU to drive the motor with specified position, velocity andacceleration parameters. Electromechanical EMA drives the piston withina cylinder by a brushless servomotor Actuator (EMA) to provide pulsatiledriving pressure to the blood pump. 110 Blood Pressure The bloodpressure signal is obtained from the Blood Pressure Sensor 527 SensingElement, embedded within the implanted blood pump. The blood pressuresignal supplies the pressure waveform for MCU to process and determinethe timing for commanding EMA eject and fill action. User InterfaceProvides LED indicators, audio alarm, buttons and LCD display. Panel 170Power The circuit is to manage the system power, including powerManagement switching, battery condition monitoring and charging control.Circuit 140 Docked Battery Provides power to the system when it is notsupported by external 150 power. Clinical Monitor Collects and displaysreal-time device waveform data; initiates 190 driver parameters settingand stores patient identification data; perform long-term conditionmonitoring and diagnosis trending analysis.

The signal acquisition, transmission, processing, and the control logicand command generation and EMA actuation to produce pressure pulse todrive the blood pump is illustrated in FIGS. 12 and 13 for theexemplified embodiments previously elucidated.

FIG. 14 depicts the trigger-detection commands for EMA piston positionin relation to the counter-pulsatile pumping. In FIG. 14 the unassistedaortic pressure (AoP) waveform is expressed in dotted line whereas solidline represents the assisted aortic pressure waveform. When the driveroperates with Auto Run mode, the driver operation is initiated and thesystem carries out a “fill-eject-fill-eject . . . ” cyclic pumping,which represents a normal synchronous counter-pulsation operation. TheMCU monitors blood pump pressure (BPP) signals (electric signal) anddetects the left ventricle end-diastole (LVED) timing. Upon detection ofLVED timing, the MCU generates a F_Trig signal. The time intervalbetween two consecutive F_Trig signals represents an instantaneouscardiac cycle interval (or period). Based on an estimated heart ratecalculated from the preceding cycle intervals, the MCU determines thetiming, the E_Trig signal, for blood pump ejection. The E_Trig signalprovides the timing to command the motor controller unit to drive theEMA according to the predetermined position, velocity, and accelerationprofiles. When the ejection stroke is completed and after an optimizeddwell time elapse, the EMA is commanded to perform a pre-fill actionwith a gentle filling speed until the F_Trig signal shows up. Uponreceiving the F_Trig signal, the EMA starts to perform a residual fillstroke at a specified piston speed.

When the MCU loses the BPP signal (electrical signal) sent from theblood pump, a washout mode is launched automatically by MCU to drive theEMA, operating at a predetermined pumping rate and driver stroke volume.The washout mode is used to prevent the formation of thrombus in theblood sac, which is a device protection mode instead of providingsynchronous circulatory support.

The para-aortic blood pump device of the present invention, with itsnon-occlusive para-aortic feature, in principle, has a bettercounter-pulsatile support efficacy as compared to the intra-aorticballoon pump (IABP). Unlike the bedridden or ambulatory IABP patientswho have to stay in hospital, the portable para-aortic blood pump deviceallows the patients to leave the hospital and have ambulatory capabilityto live a better life at home. Hence, the para-aortic blood pump deviceof the present invention may further improve patient's diseaseconditions and quality of life, in addition to the economic benefitsgained from a shorter hospital stay.

The trend of LVAD use has been plateaued in recent years, mainly becauseits application is only indicated to the terminal-stage heart failurepatient cohort. Applying early intervention LVAD therapy to theless-sick heart failure patients has long been a clinical objective,which is expected to imposing substantial impact on the future cardiacmedicine advancement provided by the broadened use of LVAD therapy.Clinical evidences have shown that certain non-ischemic cardiomyopathypatients supported by LVAD, administered in moderate-to-severe heartfailure stage, can be improved with myocardial reverse remodeling towardfunctional upgrade or sustained myocardial recovery. Nevertheless, thisintention of early intervention must be ushered by two enabling factors:an easy and safe surgical procedure, and an effective and adaptivesupport scheme accompanying disease development. Continuous-flow VADsupport is non-physiologic, which deranges the supported heart away froma normal course of recovery. The counter-pulsatile support, however, isphysiologic and meets the therapeutic requirement by providing systoliccontraction unloading and diastolic perfusion augmentation to promotemyocyte reverse remodeling. In summary, the treatment strategy providedby this para-aortic blood pump invention aligns with the earlyintervention trend development in cardiac medicine. Salutary attributesprovided by the para-aortic blood pump device, such as adaptivepartial-support, less invasive surgery and counter-pulsatiletherapeutics will collectively make the present invention a prospectivecandidate to contribute to the future advancement of heart failuretreatment.

The blood pump of each of the aforementioned embodiments is furtherdescribed below.

With reference to FIG. 13A and FIG. 13B for the schematic and sectionalview of a part of a para-aortic blood pump device installed in humanbody in accordance with the first and third embodiments of the presentinvention, the implant subsystem of the para-aortic blood pump devicecomprises the blood bump 52, the aortic adapter 54, and the driveline(or distal driveline) 57 attached to the blood pump 52. The blood pump52 comprises a rigid or semi-rigid pump housing 52 h of the blood pump52 and a blood sac 529 having its proximal end closed and distal endopen and seamlessly integrated with the aortic adapter 54. The blood sac529 is formed by an oval-shaped sac membrane 526, moreover, the bloodsac 529 is anchored via a proximal stem 530 to the proximal shell 523 ofthe pump housing 52 h and via a distal stem 540 to the distal shell 525of the pump housing 52 h. The space in the blood pump is partitionedinto a blood chamber B and an air chamber A separated by the oval-shapedflexible sac membrane 526 suspended via a pair of stress-relief stems(proximal stem 530, distal stem 540) attached to the pump housing 52 h.The blood chamber B is for blood storage and the air chamber A is forreceiving driving air. The pump housing 52 h comprises the proximalshell 523 in which a pressure sensor (or a blood pressure sensor) 527 ishermetically embedded, and the sensed pump pressure is transmittedacross the sac membrane 526, propagated in an incompressible liquid orjelly housed in a closed pressure sensing chamber 528, and finallyreceived by the pressure sensor 527. After receiving the sensed pumppressure, the pressure sensor 527 generates an electrical blood pressuresignal. The implanted subsystem components are designed with a size anda shape that can be implanted in patients with a body surface area (BSA)of 1.2 m² or larger.

With reference to FIG. 14A and FIG. 14B for the schematic and sectionalview of a part of a para-aortic blood pump device installed in humanbody in accordance with the second and fourth embodiments of the presentinvention, the implant subsystem of the para-aortic blood pump devicecomprises the blood pump 62, the aortic adapter 64, the coupler 65 anddriveline (or distal driveline) 67 attached to the blood pump 62. Thecoupler 65 is used to couple the blood pump 62 to the aortic adapter 64to access the recipient's vascular system. The blood pump 62 comprises apump housing 62 h, which further comprises a proximal shell 623 and adistal shell 625. The construct of the present blood pump 62 is similarto that disclosed in FIG. 13B, except that the distal opening OP isseparated from and independent with the aortic adapter. The coupler 65is placed around the flexible neck 643 of the aortic adapter 64. In thefollowing, we use the design disclosed in FIG. 13B to further explainthe blood pump design and the underlying design rationale.

Referring to FIG. 13B, the blood pump 52 comprises a molded rigid orsemi-rigid blood housing 52 h which further comprises a proximal shell523 and a distal shell 525. The housing 52 h has a single opening OPconnected to the aortic adapter 54 to access the recipient's vascularsystem. The opening OP of the blood pump 52 is seamlessly manufacturedtogether with the aortic adapter 54 (or the blood pump 52 and the aorticadapter 54 are integrally formed), which provides a smooth andcontinuous interface transition to the neck of the aortic adapter 54.Such integrated blood sac 529 and aortic adapter 54 assembly is attachedto the pump proximal shell 523 and distal shell 525 via a bonding to theproximal stem 530 and distal stem 540, respectively. The blood sac 529is anchored to the top of the proximal shell 523, such that a small,non-flexing circular portion of the blood sac 529 is disposed next to apressure sensing chamber 528 in the shell 523.

A miniaturized pressure sensor 527 is built into the pump shell 523 andfluid communicated to the enclosed pressure sensing chamber 528. Thisarrangement allows a continuous monitoring of the blood pressurecontained in the blood sac 529. Since the pressure sensor 527 is notblood-contacting, the long-term sensor reliability and fidelity isassured by the protection of the pump housing 52 h that isolates thesensor 527 and its electric circuit from the influence of chemicalcorrosion and protein adherence arising from the direct blood contact.

A driveline 57 end is attached to the pump shell 525 to provide timedair pressure pulses for actuating the eject or fill stroke of blood outof or into the blood pump 52. The driveline design can be multi-luminalor multi-layered so as to accommodate the electrical wires for pressuresignal transmission. Metallic coil or fabric mesh can be adopted as thewall reinforcement to enhance the anti-kink capability of the driveline57. The overall geometry of the blood flow passage in the present bloodpump is wide, along with the valveless aortic adapter design andpulsatile pumping operation, constituting a superior blood handlingproperty that avoids high shear-induced hemolysis as well as low flowspeed generated thrombus formation or thromboembolism.

The blood sac 529 of the blood pump 52 includes an innovative design tomake the sac membrane 526 durable. The blood sac 529 is an oval-shapedmembrane body of revolution to the centerline of the blood pump 52.There are two polymeric stems (proximal stem 530, distal stem 540)bonded at both housing 52 h ends, configured respectively to be in acircular disc or an annulus shape, and working as a flexing/stretchingrelief mechanism to alleviate stress concentration when attached to therigid housing 52 h. During pump ejection, the sac membrane 526 will becompressed or folded into a tri-lobe shape where the highest strainoften occurs at the creased folding line near the rim of the stemattachment (proximal stem 530, distal stem 540). This local highmembrane stress/strain arising from large membrane deformation issubstantially reduced or absorbed by the deformation of the flexiblestem rim as a bendable suspension. Notice that the tri-lobe foldingpattern is non-stationary, with creases changing from place to place asinfluenced by the gravitational direction. In fact, a patient's bodyposture and orientation including the positions of standing, sleeping,sitting, exercising, etc. may change from time to time in dailyactivities. The gravitational effect or the body force acting on thestored blood volume in the blood pump 52 is hence constantly changing,resulting in a non-stationary crease line initiation and formation. Suchrunning membrane folding line constitutes a unique fatigue resistancefeature of the present invention. It is anticipated that the presentblood pump 52 will possess a much longer durability than that of theconventional fixed folding line membrane design.

Membrane folding and expansion are intimately related to the vortex flowpattern contained in the blood sac 529. The aforementioned sac designfeatures a running folding line formation that makes the vortexstructure pattern alternatingly change in response to the foldedmembrane pattern. The washout effect in the blood pump 52 is thus strongand non-stationary, characterized by a random walk-like vortical flowmovement. Such randomness in the pump vortex flow structure helpswashout the entire blood-contacting surface without creating any fixedlow-speed zone near the membrane wall or in the crease area. It has beenobserved in animal trails that the present blood pump is verythromboresistant.

The (distal) driveline of each of the aforementioned embodiments isfurther described below.

Referring to FIGS. 5 and 6 for a schematic view of the driveline used toconnect the blood pump 92 with the driver 98. The intracorporeal(distal) driveline 991, 97 of the driveline pneumatically connects theblood pump 92 to the electro-mechanical actuator housed within thedriver 98 and also carries the electrical signals acquired from theblood pump pressure sensor 527 (see FIG. 13B). The (distal) driveline991, 97 has one end attached to the blood pump housing and the oppositeend having a small external connector for pneumatic and electricalcommunication. The (distal) driveline 991, 97 is tunneled subcutaneouslyand exits the skin. The outer diameter of the (distal) driveline 991, 97is designed to be small and the tubing material is flexible to minimizethe exit site EX stress to the patient's comfort. A portion of the(distal) driveline 991, 971 is covered with a porous fabric to promotetissue ingrowth so as to make the exit site infection resistant. Theexternalized (distal) driveline 991, 973 is secured with a shortdistance beyond the skin exit site EX.

The (distal) driveline 991, 971 and its connector are designed towithstand the tensile loads applied during surgical externalization.Post-operatively, the (distal) driveline 991, 971 is constantlyinfluenced by muscular motion-induced loads, and the (distal) driveline991, 971 is designed to withstand these loads for their intended servicelife. The externalized portion of (distal) driveline 991, 971 is alsodesigned to be biocompatible and chemically resistant to cleaning agentsand disinfectant in clinical use.

The (proximal) driveline of each of the aforementioned embodiments isfurther described below.

The (proximal) driveline 993, 99 is used to connect the (distal)driveline 991, 97 to the driver 98. The (proximal) driveline 99 has adriveline interconnector 93 at one end and a driver connector at theother end. The said driveline interconnector 93 encloses a circuitboard, which converts analog blood pump pressure signal into digitalsignal, and a vibrator that provides a tactile feedback in addition tothe audible alarms. The driveline interconnector 93 comes with a flatshape to prevent torsion from being generated to the (distal) driveline973 when the driveline interconnector 93 is anchored against thepatient's skin. Further, the driveline interconnector 93 and thedriveline outer cover are designed to be sealed and protected againstwater or moisture ingression. Since the (proximal) driveline 99 isinstalled externally, it can be replaced and/or maintained when deemednecessary, hence eliminating the surgical blood pump replacementrequired when the (proximal) driveline 99 is damaged beyond repairable.

Valveless blood pump has two advantages in blood handlingcharacteristics: 1) having no annoying valve sound and valve-inducedblood cell damage, thrombus formation and thromboembolism; 2) being morethromboresistant because the two-way pulsatile flow has better surfacecleaning effect to minimize protein adhesion and avert interfacediscontinuity-related clot formation over the blood-contactingartificial surfaces. The flow passage in the valveless pulsatile pump isuniformly much wider that those in the valved pulsatile orcontinuous-flow rotary pumps. Hemolysis (rupture of red blood cellmembrane) generally takes place at narrow flow passages with high flowvelocity gradient, such as the gaps between the valve ring and leafletof a valved pulsatile pump. In addition, low-speed recirculation orstasis zone often exists in the back side of the opened valve which mayencourage thrombus to be generated. In a sharp contrast, in a valvelesspulsatile blood pump, the shear stress applied on blood cells isliterally order of magnitude smaller, and the low-speed stasis zoneassociated with valve geometry and motion is substantially eliminated,which leads to less blood cell damage or platelet activation, less clotformation and aggregation and translates to lower dose of anticoagulantuse and easier and safer post-operative care.

FIGS. 15 to 17 shows the blood pump 62, the driveline 67 and thefeedthrough 63 according to another embodiment of the present invention.This embodiment stresses the anatomic adaptivity for an easier bloodpump placement and driveline externalization.

As shown in FIGS. 15 and 16, the driveline 67 is connected to distalshell 625 of the blood pump 62. The blood pump 62 has the oval-shapedblood sac and stem assembly 650 (including sac 629 and stems 630, 640),the pump housing 62 h (having the proximal shell 623 and the distalshell 625), and the pressure sensing system 628 embedded in the proximalshell 623. The design details of the oval-shaped blood sac and stemassembly 650, the distal shell adapter 6251, the pressure sensing system628, and the driveline 67 are substantially identical or correspondingto those of the aforementioned embodiment, and the modular andfunctional descriptions are not repeated herein.

In this embodiment, the feedthrough 63 is disposed in the distal shell625 of the pump housing 62 h for coupling the driveline 67 to the pumphousing 62 h. Further, the feedthrough 63 is configured in a body-fittedshape adjacent to the distal shell 625, making driveline connection in atangential direction to the pump outer surface. Such body-fittedfeedthrough design renders pump housing 62 h design adaptive to theanatomic space available for blood pump placement. The blood pump 62 canbe rotatably connected to the interface adapter 501 and allow thedriveline 67 be routed with best suited orientation to enable a smoothsubcutaneous tunneling and skin exit. In this way, it favors to anatomicadaptivity to the implant site geometry.

In this embodiment, the feedthrough 63 is remotely suited in the distalshell 625 while the pressure sensor 6271 (see FIG. 25A) and sensingchamber 628 are located in the proximal shell 623. More engineering workhas to be performed to separate signal transduction route from pneumaticcommunication route and assures that the blood pump 62 be sealed andprotected against biochemical fluid invasion that might damage thefidelity of signal transduction after device implantation.

FIG. 17 shows the pump housing 62 h has a superficial trench 621 formedon the outer surface of the distal shell 625 and above an overlappedbonding area DA (FIG. 16) of the proximal shell 623 and distal shell625. The superficial trench 621 is configured to let the electric wiresbe extended from the outlet of feedthrough 63, along the trench abovethe overlapped bonding area and reach the electrodes 6274 of thepressure sensor 6273 (see FIG. 25B). In some embodiments, the trench 621is sealed by a potting waterproof material and/or a ring-shaped cover tomaintain a smooth outer surface in order not to irritate or hurt thecontacted tissue.

As illustrated in FIGS. 18A and 18B, the aortic connector 50 generallyrequires an interface adapter 501 to serve as a coupling mechanism toconnect the blood pump 62 onto the target artery 60. The distal end 504of the connector 50 opposite to the interface adapter 501 is placed inthe vascular wall of the artery 60, and in fluid connection with thehuman circulation. The proximal end (the interface adapter 501) of theaortic connector 50, however, has a smooth interface transition togeometrically match with the inlet morphology of the blood pump 62. Acoupler is commonly required to integrate together the proximal end ofthe connector 50 (the interface adapter 501) with the inlet of the bloodpump 62. There are some embodiments that can be used as the aorticconnector 50. The one shown in FIG. 18A is the end-to-side anastomosisof a Dacron or Polytetrafluoroethylene (PTFE) graft 502 sutured with thetarget vessel 60, which can be used in vascular surgery. In some otherembodiments, such as the one shown in FIG. 18B, an insertion type aorticconnector 503 is used, such as the T-manifold shaped adapter 503disclosed in U.S. Pat. US 2008/0300447A1, entitled “Dual-pulsationbi-Ventricular Assist Device.”

FIGS. 19 and 20 illustrate respectively the assembly and components ofthe long-duration axi-symmetric oval-shaped blood sac and stem assembly650 design. The polymeric material chosen for these components can be,but not limited to, segmented polyurethane with various appropriatedurometers. The constituent parts of sac and stem assembly 650 includesa flexible membrane sac (blood sac) 629, a proximal stem 630, and adistal stem 640, which are all made in axi-symmetric shapes andintegrated together into an assembly of body of revolution relative to acommon centerline 62C of the blood pump 62. The proximal stem 630 islocated at the proximal end 6291 of the sac 629, and the distal stem 640is located at the distal end 6292 of the sac 629.

FIG. 19 shows the integrated sac and stem assembly 650 of which the endof the distal stem 640 is wrapped and bonded with the inverted membrane62A at the distal end of the sac 629. FIG. 20 illustrates theconstituent parts before bonding. In general, the sac 629 is made by dipmolding while the stems 630, 640 are injection molded. There is nopreferred azimuthal angle for sac deformation to be biased. In theory,thin-walled sac constructed in axi-symmetric oval shape will buckle intoa tri-lobe configuration 6293, as shown in FIG. 21, when pressuredifferential across the membrane exceeds certain threshold. Suchmembrane buckling only matters with the final tri-lobe configuration6293 (eigenmode) and where the creases 6294, or folding lines, shalltake place is decided by the initial perturbation that triggers theinitiation of buckling instability. The thickness uniformity incross-sectional planes cut perpendicularly to the centerline (or theaxis of revolution) 62C of the assembly 650 of the blood pump 62 iscritical. Care must be exercised to maintain a high-precision sacmanufacturing such that an axi-symmetric shape is assured. In real lifeapplication, gravity direction stands out as the dominant factor infolding line initiation. Postures of device recipients constantlychange, so is the gravity direction relative to the blood pumporientation, according to the daily activities the patient isundergoing, such as standing, sitting, exercising, sleeping, etc. Thecreases 6294 of sac deformation, hence, appear in a random walk-likepattern which disperses the high-strain creases non-stationarily overthe entire sac. Avoidance of high-strain region dwelling at fixedlocation, therefore, is the key design guideline to make the saclong-duration.

The embodiment of the present invention innovates a running folding lineattribute which makes the high-strain location appearingnon-stationarily in the membrane to prolong sac fatigue life. Thedetrimental stress concentration phenomenon frequently associated withthe flexing blood sac is hence improved. Based on this fundamentalchange in flexing pattern behavior, the fatigue life of membrane willsignificantly increase attributable to this non-stationary folding lineformation characteristic that disperses the high strain areas all overthe sac. Further, a salutary outcome accompanying this non-stationarysac deformation pattern resides on the vortex washout effect enhancedwithin the blood sac. The sac surface will be washed more thoroughlywith a random walk-like vortex formation and traversing. The probabilityof producing constant low-speed recirculation zone dwelling in thenear-wall region or creases of the folding lines, hence, will be greatlyreduced, resulting in a long-duration, thrombo-resistant blood pumpdesign.

FIGS. 22, 23A and 23B show an exemplary embodiment of how an integrationmethod is adopted for mounting the blood sac assembly onto the pumphousing 62 h as well as joining a driveline 67 to the proximal shell623. The distal driveline 67 has its first end connected to the bloodpump 62 at the feedthrough 63 and the second end manufactured as a solidconnector 678 having electrodes 6781 flushed mounted and covered by abend relief 679.

The blood sac 629 is anchored onto the pump housing 62 h, which includesa proximal shell 623 and a distal shell 625, to facilitate pump fill andejection actions. In general, the flexural properties of the sac 629 andthe housing 62 h are vastly different. To accomplish a long-duration sacdesign, it requires an intermediate suspension to be installed to renderthe pump assembly continuous in structural property transition, inparticular the membrane flexural deformation. A pair of flexible stems630 and 640 is adopted as the suspension that integrates the blood sac629 with the housing 62 h. As shown in FIG. 23A, the proximal stem 630,configured in a disc shape, connects with the proximal shell 623;whereas the distal stem 640, in an annulus form, connects with thedistal shell 625. Mechanically, the proximal and distal stems 630, 640work as a stress-relief suspension, which not only holds the blood sacwithin the pump housing 62 h but also avoids stress concentration tooccur at interface attachment, hence prolonging the service life of thesac 629.

As shown in the bottom of FIG. 23A, the distal shell 625 includes anextension, termed distal shell adapter 6251, which is to be coupled withthe aortic adapter 14. This distal shell adapter 6251 has a first end6252 attached to the sac 629 and the second end 6253 featured like abeak to be coupled with the interface adapter 501 (depicted in FIGS. 18Aand 18B). The first end 6252 of the adapter 6251 matches with the distalend of the sac 629 smoothly. The opposite second end 6253, however, isconfigured to be paired with the interface adapter 501, and the couplingdesign goal is to minimize the interface discontinuity to avert clotformation. The adapter 6251 has a flange structure 6254 which isdisposed in the middle region of the distal shell adapter 6251, workingas a lock element to be received by the interface adapter 501.

During surgical operation, the closed-end sac design of the valvelessblood pump 62 would attract air and agglomerate air bubbles in the sactop due to buoyancy force. As shown in FIGS. 22 and 24, a de-airing port66 is hence installed or made in the proximal shell 623, in which anarrow channel 661 is provided above the stem 630. An integrated sac andstem septum 6301 as an extension from the channel 661 is used to allowde-airing needle to pierce through and enter into the blood chamber forair removal. In some embodiments, the channel 661 is extends alongsidethe centerline 62C. After the blood pump 62 is anastomosed with thetarget artery 60, the trapped air will be pushed by the arterial bloodpressure and emerges and aggregates over the dome space of the sac 629.A thin needle is used to piece through the de-airing port 66, across thechannel 661, penetrating the sac and stem septum 6301, and finallyreaches the interior of the blood sac 629 to discharge the accumulatedair. The integrated sac and stem septum 6301 beneath the de-airing port66 is relatively rigid and non-flexing, which will maintain the piercedsac 629 without further structural failure due to crack propagationinitiated at the pierced slit when subject to cyclic pulse pressure andthe neighboring sac stretching and folding.

As illustrated in FIGS. 23A and 25A, the pressure sensing mechanism 627is embedded in the proximal shell 623. FIG. 23A illustrates thesectional details of an integrated proximal shell 623, feedthrough 63,and driveline 67. FIG. 25A depicts the profile of the proximal shell 623that connects a feedthrough 63 extended from the dome of the shell 623for pneumatic and signal communication with the driveline 67.

The pressure sensing mechanism 627, as detailed in FIGS. 25A and 25B,has a pressure sensor 6271, which is hermetically housed in a metalcanister, including a first space 6272 for fluid communication and asecond space 6273 for accommodating the micro electro-mechanical system(MEMS) pressure transducer and the associated electronic circuit. Thereare multiple electrodes 6274 stuck out from the base of the second space6273, to be connected with the electric wires 6702 of the driveline 67(FIG. 26). The second space 6273 is closer to the driveline 67 than thefirst space 6272. The small tube of the first space 6272 is open tofluid communicate with the sensing medium. Biocompatible fluid or jellyis used as the pressure transmission medium. A cavity or a pressuresensing chamber 628, situated in the proximal shell 623 and adjacent tothe first space 6272, is created to allow sensing fluid be enclosed in.This pressure sensing chamber 628 has a distal end separated with theblood chamber by the sac membrane 629. The pressure sensing chamber hastwo side arms: first arm 6281 and second arm 6282, wherein the arm 6281is used for installation of pressure sensor 6271, and the arm 6282 isused for filling and sealing a sensing medium. The blood pressure pulse,hence, can be transmitted across the sac membrane 629 and hydraulicallycommunicated with the MEMS sensor 6271 remotely located in the secondspace 6273.

An embodiment of the present invention innovates a pressure-based bloodpump control method and sensor design. A miniature MEMS pressure sensoris adopted with electronic circuit packaged and embedded in the pumphousing wall. In principle, MEMS sensor die is very durable owing to itsintrinsic micro-scaled structure. Sensor durability, in fact, depends onthe packaging design. The present pressure sensing system 627 isnon-blood contacting and isolated from the corrosive biochemical effectsassociated with blood, thus providing long-duration signal acquisitionand transmission that is required for long-term implantable assistdevices.

The driveline 67 works as a communicator for electric signaltransduction and pneumatic pulse pressure transfer between the bloodpump 62 and the driver 98. A representative multi-layered driveline 67in the present invention is shown in FIG. 26. In this embodiment, thedriveline 67 has a pneumatic lumen (or inner pneumatic tubing) 6701, aplurality of electric wires 6702, a middle pneumatic tubing 673, a coil674 (such as a metallic coil), an outer layer tubing 675, a tether 676,a silicone jacket 677, a rigid driver connector 678, and a protectivebend relief 679.

The central portion of the driveline 67 accommodates the pneumatic lumen6701 (or air passage, inner tubing) with a lumen diameter around 2-5 mm,depending on the preference of choice between lower energy consumptionor low-profile for easiness of surgery. The electric wires 6702 forsignal transmission are embedded in the wall of the driveline 67. Thereare variants of driveline design that may be adopted. Aside from themulti-layered driveline design shown in FIG. 26, the driveline 67, forinstance, can also be multi-luminal to facilitate electric wires 6702embedment in several smaller lumens and allow pulsed air to flow in alarger lumen 6701, as shown in FIG. 27. One of the smaller lumens can beinstalled with tether 676 so as to limit the stretching of the driveline67 and protect the electric wires from damage when subject to the pullforce of externalization.

The inner tubing, or pneumatic lumen 6701, is received by the middletubing 673 with reinforcement being sandwiched in between. Between theinner and middle tubing 6701 and 673, the coil 674 (or fabric thread ormesh) can be reflowed (thermally co-molded using heat shrink) as areinforcement to the driveline wall, making the driveline 67 flexiblebut kink resistant. The outer layer tubing 675 covers the inner andmiddle pneumatic tubing 6701 and 673, and can be employed to cover thespirally wrapped electric wires 6702 as a protective sheath. In someembodiments, a non-distensible tether 676 can be disposed between theouter tubing 675 and the silicone jacket 677 of the driveline 67, tostrengthen the tensile resilience required during externalization of thedriveline 67. Clinically it has been demonstrated that silicone jacket677 is least irritative to the subcutaneous tissues and has the lowestdriveline infection rate.

In this embodiment, the pneumatic lumen 6701, the metal coil 674, themiddle tubing 673, the spiral electric wires 6702, the outer tubing 675,the tether 676, and the silicone jacket 677 are packaged into a body ofthe driveline 67. The proximal end 671 of the driveline 67 is to beplugged into a receptacle housed in the driver 98. The rigid drivelineconnector 678 of the driveline 67 is configured to be received by thereceptacle of the proximal driveline interconnector 93 or the driver 98.The rigid driver connector 678 is flush mounted with a plurality ofelectrodes 6781 (for example, four electrodes 6781 in FIG. 23B) solderedwith the electric wires 6702. A protective bend relief 679 (see FIGS.23B and 26) is placed over the joint segment of the driveline 67 and thedriver connector 678, in order to keep the driveline 67 from beingkinked at the joint. The proximal end of the driveline, including thedriver connector 678 and the bend relief 679, is kept in low-profile sothat it is easy to exit the skin without creating undesirable tunnelingtrauma.

The connection of the driveline 67 onto the blood pump 62 isaccomplished via a feedthrough 63, as illustrated in FIGS. 22, and 23A.The feedthrough 63 can be placed in the proximal shell 623 or in thedistal shell 625, depending on the anatomy where the blood pump 62 is tobe implanted. Integrating feedthrough 63 with pump housing 62 h maychange the overall outer blood pump configuration and direct thedriveline 67 in certain direction to meet the implant requirementsincluding driveline externalization route, post-operative skin care anddevice usability.

As shown in FIGS. 23A, and 25A, the feedthrough 63 has a first portion631 as an extension of the proximal shell 623 in which the pneumaticlumen 6701, the tether 676 and the electric wires 6702 of the driveline67 are coupled via an anchor adapter 672, wherein the anchor adapter 672connects with the distal driveline 67 to allow driving air to passthrough the pneumatic lumen 6701. The feedthrough 63 further has asecond portion 632 which is interlocked with the first portion 631working as a bend relief of the driveline 67. The first portion 631 isthe location where electric wire connection, tether anchorage, andpneumatic lumen bonding and seal with the housing take place. It isrequired that electric wires must not be exposed to implant site tissueand have to be well protected against pull force exerted duringdriveline externalization. Also, the connection of pneumatic lumen 6701with blood pump 62 need to be pneumatically and electricallyleakage-free. As shown in FIG. 25A, these mentioned blood pumpintegration tasks are performed in the first portion 631. The secondportion 632, however, is employed to accommodate and seal theseinterface joint elements, working as an outer protector that protectsthe joint from mechanical straining and environmental fluid or moistureinvasion.

The modular design pertaining to the first embodiment of the presentblood pump invention has been disclosed in FIGS. 19 to 27. In thisillustrated embodiment, the blood pump 62 includes an axi-symmetricoval-shaped blood sac and stem assembly 650 (including a flexiblemembrane sac 629, a proximal stem 630 and a distal stem 640); a pumphousing 62 h having a proximal shell 623 and a distal shell 625; and apressure sensing system 627 embedded in the proximal shell 623. Adriveline 67 is connected to the blood pump 62, including a pneumaticlumen 6701 and electric wires 6702 included in the wall thereof. Tointegrate the driveline 67 with the pump housing 62 h, a feedthrough 63is used to accomplish both electric and pneumatic communication betweenthe driveline 67 and the blood pump 62.

As shown in FIGS. 19 and 20, the polymeric manufacturing and bondingmethod integrating together the blood sac 629 and stems 630, 640 hasbeen disclosed in the previous section. The design and manufacturingessentials lie in maintaining a high-precision axi-symmetry in partsmanufacturing and bonding of the sac and stem assembly. The pressuresensing system 627 and the feedthrough 63 are installed in the rigidpart of the proximal shell 623. As shown in FIGS. 22, 23A, and 25A, acompact feedthrough 63 design is illustrated. It can be observed that,by the compact feedthrough 63, the electric wiring and connection can beachieved more robust and fault tolerant.

FIGS. 28A and 28B depict some flow patterns associated with para-aorticcounterpulsation. Over end-diastolic and early systolic phase of leftventricular ejection, the blood pump undergoes pump fill and draw aorticflow into the pump (FIG. 28A). Both upstream and downstream blood aroundthe connector will be sucked into blood pump by making a sharp 90degrees flow turn. Flow separation and low-speed recirculation zonesT-201 hence will be created. Also, extraordinarily high-shear willappear at the corner region of the T-junction. On the other hand, duringdiastolic phase after aortic valve closure, the stored blood in the pumpwill be ejected back into the circulation, creating impinging flow onthe opposite aortic wall (FIG. 28B). This side dump, impinging flowinvolves very high local pressure at the impingement point T-202, theso-called stagnation point where flow speed is literally zero and allkinetic energy associated with flow velocity is converted into apotential energy termed total pressure. Such high-pressure impingingflow may induce vascular maladaptation including smooth muscle cellproliferation and the resultant wall stenosis, and risk of aorticdissection due to persistent local hypertension. All thesenon-physiologic flow pattern and the induced high-pressure, high-shear,low-speed recirculation phenomena prevail in the vicinity of theT-juncture region. This turbulent, complex flow anomaly will decay ordiminish in a distance of 3-5 times the implanted arterial lumendiameter. The present insertion type aortic adapter is designed to havean inserted conduit length of 5-7 cm, which covers most of thepump-induced non-physiologic flow region. As the implant site aorta isshielded by the inserted aortic adapter, the biologic vascular wall willbe isolated from the influences of the pump-induced pathological stressconditions, hence protecting the implant site artery from remodelingcomplications induced in the acute or long-term period.

In counterpulsatile support, pump fill and ejection are alternatinglyactuated in synchronization with cardiac rhythm, which generates aspecial T-juncture flow as shown in FIGS. 28A and 28B. This insertiontype aortic adapter 14 is further detailed in FIG. 29, a perspectiveview, and in FIG. 30, a sectional view, respectively.

The aortic adapter 14 is mold injected with its internalblood-contacting surface 141 being manufactured ultra-smooth andcontinuous without any parting lines. Silicone or other polymericelastomers can be used as the material. The aortic adapter 14 comprisesa conduit (or an inserted conduit portion) 142 which is to be insertedin the aorta 95 (see FIG. 5) and a neck (or an extruded neck portion)143 that connects to the blood pump. In this embodiment, the neckportion 143 has a neck body 1431 and an extension part 1432 disposed onthe neck body 1431, wherein the extension part 1432 protrudes from theneck body 1431, and the maximum inner diameter of the extension part1432 is larger than the maximum inner diameter of the neck body 1431.When the neck portion 142 is connected to the blood pump 62, theextension part 1432 snuggly embraces the inlet adapter 6251 of the bloodbump 62, and the neck body 1431 is disposed around by the coupler 25which integrates the aortic adapter 6251 to the blood pump 62.

The entire aortic adapter 14 is thin-walled to maximize the flowefficiency. To strengthen the thin-walled structure, a pair of Nitinoltruss (or truss rings) 144 is embedded around the two ends of theconduit portion 142 of the aortic adapter 14.

FIG. 29 is a transparent view showing the locations where the Nitinoltruss 144 is embedded. Further, the wall thickness of the conduit 142 isgradually thinning toward the conduit end 145. The function of thegradually thinning wall thickness is two-fold. First, it minimizes thegraft/host junction discontinuity and renders the interface clotformation rate always be lower than the thrombolysis rate provided bythe contacted endothelium. Second, the compliance of the conduit isbecoming softer toward the conduit ends 145, resulting in acompliance-matching effect when joined with the aortic lumen.

One of the complications that plagued the large stent graft implantationis the endo-leak problem. Type-I endo-leak means the seal of the graftend to the endothelial lumen of the implanted artery is not complete,causing gap created between the graft leading-edge and the arteriallumen. Leaked blood will be trapped and jammed in the gaps andsolidified into clot and finally becomes fibrous pseudo-intima whichwill grow uncontrollably in time. Not only the pseudo-intima willobstruct the grafted artery, but also it may signal and stimulatecoagulation mechanism to attract platelet adhesion and leads tothrombotic adverse events to occur. The solution to resolve suchendo-leak problem is to have a tight seal of the aortic adapter 14 withrespect to the attached lumen surface. The present aortic adapter 14comes up with a compliance-matching design concept that enables thesemi-rigid conduit ends 145 seamlessly attach to the arterial lumen whensubject to pulsatile blood pressurization. The outside diameter 146 ofthe aortic adapter conduit 142 is slightly larger than the luminaldiameter with an oversize ratio (defined as percentage increment inconduit diameter 146 relative to luminal diameter) in the range of 3-10%conditioned at certain nominal blood pressure (say 120 mmHg). As bloodpressure fluctuates between systole and diastole, or under the pulsepressure generated by counterpulsatile support, the compliance-matchingconduit ends 145 will dynamically expand and contract in response to thepressure pulsation without creating interfacial gaps.

Generally speaking, a thin-walled tubing made of elastomer is flexibleand tends to be compliance-matching, but it is often not strong enoughto withstand the compression force exerted due to device oversizing,causing wall buckling of the inserted adapter and the resultant massivebleeding. Hence, the combined use of Nitinol truss structure 144 and theelastomeric substrate with appropriate hardness is important. As shownin FIG. 30, in this design, the radial stiffness provided by the Nitinoltruss 144 will help support the aortic adapter 14 without buckling, andthere is a distance “X” between the outmost boundary 1441 of the truss144 and the conduit end 145. In some embodiments, this distance X shouldbe assessed and correctly defined. With the support of the Nitinol truss144 as a distensible frame, the gradually thinning conduit end 145 willnot collapse or wrinkle, which remains in circular shape against theattached lumen wall and dynamically seals with the lumen. Notice thatthe aortic adapter 14 can expand and contract in response to thepressure pulsation, and the seal effect is accomplished in a dynamicmanner that the aortic adapter 14 and the wall of the aorta 95 expandand contract together as a whole to seal the conduit end 145 withoutcausing bleeding complication.

Illustrated in FIG. 31 is a representative embodiment of the Nitinoltruss 144 which is typically made from a laser-carved Nitinol tubefurther enlarged under a sequence of expansion and a heat treatment.FIG. 31 shows the two-dimensional expanded view of the truss ring 144.Each truss has a plurality of wavy structures 1441. The truss 144 isself-expandable, which can be folded or crimped into a smaller prepackeddelivery configuration and expands to resume its original configurationwhen released after being placed at the desired location.

A convenient measure of conduit rigidity (inverse of compliance) can berepresented by the so-called lateral stiffness (LS) whose measurementmethod is illustrated in FIG. 32. LS is defined by the applied force perunit length F divided by the corresponding radial deflection Y. For thepresent aortic adapter, suitable LS range is 0.01-0.05 Nt/mm2. Bothembedded Nitinol truss 144 and silicone or elastomer substrate willcontribute the structural compliance to the co-injected aortic adapter14. It is best to have an equally distributed compliance so that thestretch and contraction of the composite conduit wall will result in aminimal interlayer delamination tendency to increase the fatigue life ofthe adapter 14.

The aortic adapter 14 is configured to be connected to the blood pump 62to facilitate circulatory support. A quick-connector type coupler isinvented herein. Illustrated in FIG. 33 are the exploded view of thecomponents of the coupler 25 that integrate together the aortic adapter14 and the blood pump 62. The present coupler 25 includes a flange base252, a pair of collars 253, and hinges (or a hinge assembly) 254 thatjoin together the collars 253 with the flange base 252. Spring coils (ora spring coil assembly) 255 are loaded in a hinge joint 256, maintainingthe collars 253 in an open position when unlocked (FIG. 34A). Thelocking mechanism is a latch 257, made of slotted leaf spring and fixedby a slab 2571 welded to one of the ends of the collars 253. The flangebase 252 has a substantially circular-shaped structure, and each collar253 has an arc-shaped structure. The hinge joint 256 is located at thefirst side 25251 of flange base 252, and the collars 253 are pivotallyconnected to the hinge joint 256 and rotatable to the hinge joint 256and the flange base 252. In some embodiments, the coupler 25 and theaortic adapter 14 belong to portions of an aortic adapter assembly.

FIG. 34B shows the picture of the coupler 25 in locked configuration, inwhich a leaf spring latch 257 is dropped down from a ramp 258 to assurethe coupling is safe without the concern of detachment. The collars 253are grooved internally as shown in FIG. 35. Integration of aorticadapter 14 to the blood pump 62 is accomplished through a clampingmechanism using the deformable adapter proximal end 147 (FIG. 30)serving as a “gasket” between the connected rigid flanges 252, and 81 ofthe coupler 25 (see FIG. 35) and the blood pump inlet adapter 6251,respectively.

In particular, quick-connection type locking can easily be carried outby closing the collars 253 that will be latched without a concern ofunintentional unlocking, as depicted in FIGS. 34B and 35. The leafspring latch 257 is installed at the tip of one collar 253. Duringcollar closing, this latch 257 will be bent as it slides on a ramp 258on the opposing collar 253 in the course of locking. As the latch 257clears the top of the ramp 258, it will drop down to the base of theramp 258 by elastic restoring force, working as a safe for preventingincidental latch unlock or collar opening attributed to pump vibrationor rocking in long-term use. For a pump explant or exchange thatrequires module decoupling, the latch 257 can be bent and lifted upwardby a tool, permitting an unlocking force to be exerted to rotationallyopen the collars 253 and hence disengage the blood pump 62 from theaortic adapter 14.

A butt joint design is not feasible for connecting two smooth-surfacedtubing adapters in a blood stream. In most clinical applications, theconnected graft is with rough surface to promote endothelialization sothat tiny interface discontinuity in the blood stream will be “smoothedout” by the ingrown cells and proteins. The present aortic adapter 14adopts smooth surface approach to avoid thrombotic adverse events tooccur. The blood flow in the aortic adapter is bi-directional inresponse to the ejection and filling action of the counterpulsatilepumping, as depicted in FIGS. 28A and 28B. Such strong bi-directionalflow and surface washing effect will easily dislodge any neon blood clotnewly formed on the rough surface. Hence, smooth surface design isconsidered more suitable and safer for the present invention. Theinterface of two joined smooth surfaces in blood stream requires acareful mechanical and hemodynamic design to avert the thrombotic eventsto occur in situ. In the following, the rationale and design methodassociated with such a novel joint invention is disclosed.

FIGS. 36A and 36B show respectively the two fundamental interfacediscontinuities that exist in a butt joint connection, such as the steps101, 102 or the gap 103 produced between an adapter AB1 (such as anadapter 6251 of the blood bump 62) and an adapter AB2 (such as theaortic adapter 14). The discontinuities shown in FIGS. 36A and 36B areexaggerated and typically in precision machining such jointdiscontinuities are within 10-50 microns, which is big enough to causeclot and thrombus formation.

In practice, tolerance inevitably exists in matching two separate bodieseven if the machining of each body is perfectly performed. FIG. 36Adepicts a misaligned joint of two bodies, of which everything related toparts manufacturing is correctly done except the centerlinemisalignment. Forward-facing and backward-facing steps 101, 102 will beproduced and the stagnation flow in the step regions 101, 102 is theorigin that clot or thrombo-emboli will be generated. In FIG. 36B, aninterface gap 103 is created due to non-parallel matching of theconnected bodies. The gap 103 attracts blood cells to accumulate andfurther grow into pseudo-intima and such intima growth often isuncontrollable, resulting in blocking the entire blood flow passage inaddition to the thrombo-emboli shed from the intimal surface. Interfaceerrors associated with butt joint may exacerbate when the connectedbodies are non-rigid. The present aortic adapter 14 is semi-rigid, whichcan be forced into butt joint connection with deformed configuration andenlarged interface discontinuities. Hence, to accomplish the presentsemi-rigid aortic adapter connection with blood pump, a novel connectionmethod must be invented, as disclosed in the following.

As shown in FIGS. 37 and 38, in some embodiments, the blood pump 62 hasan inlet adapter 80, comprising a flange 81, a beak 82 and a base 83,forming an extension of the housing of the blood pump 62. Multipleeyelets 86 are equipped for joining the inlet adapter 80 with the bloodpump 62.

The inner diameter 84 of the beak 82 is slightly greater than the innerdiameter 148 (see FIG. 30) of the neck 143 of the aortic adapter 14. Thecontact area between the beak 82 and the adapter proximal end 147 is anannular cone surface (or a shallow inclined surface or ramp) 149 (FIGS.30, and 35). The cone angle of the surface 149 is substantially in therange of 30-60 degrees measured from the centerline of revolution of theinlet adapter 80. In the initial locking engagement, the collars 253,which have inward grooves 2531 (FIG. 34A), will catch the flange of thebase 252 and the beak flange 81 loosely. Along with collars 253 closing,the flanges 81, 252 (of the beak 82 and the coupler 25) will be receivedand squeezed by the collar grooves 2531, hence compressing thesandwiched silicone end 147, and generating the clamping force requiredfor a firm connection.

The clamping force generation mechanism is graphically shown in FIG. 35.There are two steps 2521 and 2522 that are responsible for creatingclamping forces. Prior to collar closing initiation, the step 2521should be engaged in the slot 1433 of the aortic adapter neck 143 (FIG.30). Such engagement is accomplished by folding the neck 143 first, andthen insert the deformed neck 143 across the adapter flange 252, lettingthe elastic restoring force of the aortic adapter 14 to resume thefolded neck 143 back to its original circular shape and allow the step2521 be engaged into the slot 1433. The groove height Z of collar 143controls the squeezed deformation of the aortic adapter end 147.Referring to FIG. 35 it can be found that the clearance Z0, in fulllocking configuration when collars 253 are closed and latched, issmaller than the aortic adapter end width Z3 (FIG. 30). Speculation ofthe assembled geometry shows that Z0=Z−Z1−Z2, wherein the Z1 and Z2 arethe flange thicknesses of the clamped counterparts as shown in FIG. 35.In general, Z3 is greater than Z0, hence, the strained aortic adapterend 147 will generate clamping force required for a sealed connection ofthe beak flange 81 together with the collar flange base 252. The strainof the silicone flow adapter end 147, defined as (Z3−Z0)/Z3, in therange of 10-30%, suffices to guarantee a reliable sealed connection.

FIG. 39 illustrates the joint characteristic of the present connectionof the beak 82 with the adapter cone surface 149. When connected, thebeak leading edge 85 and the cone surface 82 will sink into thesemi-rigid ramp surface 149 of the aortic adapter 14 with a depthcomparable to the leading-edge radius, typically 30-50 microns, of thebeak leading edge 85. In FIG. 39, dotted line and number in parenthesesrepresent the beak in initial contact while solid line and numberswithout parentheses represent the locked relationship. Notice that theinterface discontinuity is reduced by the cone surface depression fromits original shape (the dotted line). The width of the collar groove2531 controls the interference fit of the coupling. As previouslyexplained, the elastic aortic adapter end 147 will be compressedapproximately with an 10-30% strain to provide the required couplingforce for a leak-free integration against pulsatile pumping.

The present design of interface connection between the blood pump 62 andthe aortic adapter 14 has two hemodynamic merits for reducing thrombusformation in-situ. First, there will be literally no step or gap typejoint discontinuities generated as observed in the conventional buttjoint connection. Second, stasis flow located in the interface of thebeak leading-edge 85 can be minimized. Hence, blood stream flowing overthe connected interface will be maintained with high-speed,substantially improving the butt connection drawback, namely theforward-facing or backward-facing steps 101, 102 or the gap 103 createdat the interface.

The present cone surface 149 is ramped with an inclination angle to thestream direction. Such ramp interface design averts step or gap begenerated at joint due to limited manufacturing precision or matchingeccentricity associated with conventional butt connection. Nevertheless,this shallow, cone-shaped ramp 149 has an intrinsic shortcoming infulfilling a concentric centerline alignment of the joined counterparts.The present coupling of the aortic adapter 14 with the inlet beak 82 hasno strict lateral constraint to assure coupling alignment. To connect arigid beak 82 with a semi-rigid aortic adapter flange ramp 149concentrically, a simultaneous catching of the collars around the entireperipheral rim of flange base 252 is critical. When a simultaneouscatching/locking engagement fails to be accomplished, the initiallycaught adapter flange ramp 149 will be strained more than other freeportion, creating a tendency to tilt or disposition the rest contactsurface leading to an eccentric pump connection. Such an eccentricconnection often is the causal factor that generates step or gap at theinterface that induces thrombus formation. This drawback is remedied byhaving the flange contour 259 (FIG. 34A) of the distal flange of thecollars 253 configured in such a way that the locking engagementsimultaneously includes all circumferential contact areas. When locked,the contacted edge of the metallic beak 82 will sink slightly into thecompressed silicone ramp 149 with controlled depth and further reducesthe interface discontinuity when exposed to blood stream. Hence, theconventional interface thrombus can be substantially minimized orannihilated with a moderate administration of anticoagulant regimen.

Structural deformability and method of delivery involved in the presentaortic adapter confers a special design feature of the presentinvention. Material elasticity consideration, in fact, need to becarefully incorporated in the present design. Surgically deliver aninsertion type graft into aorta via incised aortic wall is challengingin the sense of peri-operative safety and long-term reliability. Thematerial chosen for the present aortic adapter 14 should have a presetmemorized shape. During device delivery, the adapter 14 is first crimpedinto a smaller delivery configuration, and such delivery configurationguarantees a quick and safe device implantation. After the crimpedaortic adapter 14 is placed at the intended implant site, the deliveryconfiguration shall be released to self-expand to its original memorizedshape.

Prior to aortic adapter insertion a hole of diameter 12-14 mm ought tobe made in the aortic wall. In making such an access hole, care must betaken to avoid making any cut edges that may become a crack initiationpoint when wall distension is required for device insertion. Aside-biting aortic punch, as disclosed in U.S. patent application Ser.No. 17/034,036, is an ideal tool for making a large hole in the aorta.With one bite of punch a sound hole without any fractured edges can bemade successfully.

The aortic adapter 14 morphologically includes two circular tubes joinedtogether into a T-shaped flow communicator for para-aortic circulatorysupport enforcement. The conduit wall is typically 1-2 mm in thicknessand the material used is polymer such as silicone or polyurethane withappropriate hardness, for example, of Shore A 80-90. The crimpeddelivery configuration differs substantially from the commerciallyavailable large stent graft covered by Dacron or PTFE(Polytetrafluoroethylene) fabric. In FIG. 40 illustrated the crimpedform of the aortic adapter 14 (Nitinol truss 144 is embedded anddeformed with the polymer substrate). The aortic adapter 14 is folded bycrushing the inserted conduit portion 142 and the T-neck (extruded neckportion) 143 is squeezed and flattened accordingly and sunk into thefolded adapter 14 as shown in FIG. 40. Approximately, the foldedconfiguration has a diameter roughly half of the original unfoldedcircular diameter.

This folded adapter can be held fixed by string tightening. For example,as shown in FIG. 40, three fixation strings can be placed around the twoedge and center of the conduit and many other fixation methods can bethought of. FIGS. 41A, 41B, 41C and 41D show the four representativestages of a delivery of the aortic adapter 14. The first stage (see FIG.41A) depicts the initial penetration of the crimped prepack across theaccess hole while the prepack is inclined with an angle to the axis ofthe aorta 95. The second stage (FIG. 41B) illustrates the completeinsertion of the delivery configuration into the aorta, where theprepack is pushed through the access hole with the proximal end beingrotated and just dropped into the access hole. The completely insertedprepack is then retracted to have its crimped neck 143 aligned with thepunched access hole (FIG. 41C). The string constraints will be releasedand the prepacked delivery configuration resumes back to its originaldeployed configuration by elastic self-expansion (FIG. 41D). Thereleased aortic adapter 14 will snuggly be embraced by the aortic lumen,guaranteed by a proper oversize ratio selected prior to delivery. Byslightly deforming the T-neck 143 the flange 252 of coupler 25 (FIGS. 33to 34B) can be mounted onto the T-neck 143 ready for the blood pump 62to be connected. The blood pump connection can therefore be easilyaccomplished by seating the inlet beak 82 onto the T-neck cone surface149 followed by closing the two collars 253 of the coupler 25 for a firmdevice integration.

Additional safety measures can be applied to enhance the hemostasis andstability of the implanted para-aortic blood pump system. Para-aorticplacement of blood pump inevitably involves lateral force (perpendicularto the longitudinal direction of the aorta) and torque exerted on theaortic adapter 14 due to the weight of blood pump 62 and the pumpingforces generated by counterpulsatile support. Such device relatedexternal forcing may affect the long-term remodeling of the implant sitevascular structure. A purse-string suture can be placed in theadventitial layer around the access hole. The purse-string suture canadditionally tighten the aortic wall against the inserted adapter 14 andworks as a protective measure to prevent the enlargement of the accesshole. Moreover, surgical tapes can be looped and tightened around thetwo ends of the conduit 142, strengthening the integration of theinserted aortic adapter 14 and aorta as a whole. Freedom from endo-leakcan be doubly assured by the compliance-matching design and the bandingof the looped tapes. Sometimes, blood pressure may elevate beyond theupper bound that endo-leak free can be assured by compliance-matching.Under such extreme condition, surgical tapes come into play working as ahard limiter that seals the detached adapter ends and assures hemostasisbe maintained.

The step-by-step demonstration of implanting the aortic adapter 14 isdetailed in FIG. 42. A crimped prepack form is prepared prior to thestart of implantation. After left thoracotomy to expose the targetthoracic artery, a cross-clamping distance around 10 cm spanning theimplant site is defined. The access hole to be punched in the aorta isfirst marked with hole periphery identified. A purse string suture isthen sewn outside the hole periphery in the adventitial layer. The aortacan be partially dissected from the surrounding connective tissue and apair of surgical tapes can be looped around the aorta. Cross-clampingand aortic adapter insertion is performed after the above preparationwork is done. These insertion steps are described in a sequential orderillustrated in FIG. 42. First, the aorta is cross clamped to provide anisolated segment without bleeding concern. Then, a large access hole foraortic adapter insertion is made using a custom aortic punch. The foldedadapter prepack is then inserted and placed into the cross-clampedaortic segment as illustrated in FIGS. 41A, B, and C, followed by therelease and restoration of the folded adapter to its original deployedform (FIG. 41D). Purse string and tapes are then tightened as an extraprotection against endo-leak at hypertension. The coupler is theninstalled with its adapter flange 2521 seated into the slot 1433 of theaortic adapter neck, ready to receive the blood pump 22 to be connected.The self-alignment capability of the coupler design enables the beak 80of the blood pump 62 be properly positioned and locked together with theaortic adapter 14. The rest implantation steps are conventional,including cross clamp release, blood pump deairing and the initiation ofpump support. In general, for a trained surgeon, the cross-clampingperiod required for aortic adapter insertion is around 10 minutes.During this cross-clamping period the abdominal organs will be deprivedof blood perfusion and ischemic injury could potentially be incurred. Tomitigate this potential surgical insult to the organs, partialfemoral-femoral extra-corporeal membrane oxygenation (ECMO) support canbe administered to perfuse the abdominal organs and the lower limb.However, whether or not to employ ECMO support is to the discretion ofthe surgeon. Usually, an ischemic time of 20 minutes can be tolerated bya healthy patient.

In summary, an embodiment of the present invention provides aventricular assist device, including a blood pump, a driveline and afeedthrough. The blood pump includes an axi-symmetric oval-shaped bloodsac and stem assembly, including a flexible membrane sac, proximal stem,and a distal stem, wherein the flexible membrane sac is attached withthe proximal stem and the distal stem as a stress-relief suspensionmechanism; a pump housing, including a proximal shell and a distalshell, wherein the stress-relief suspension mechanism is coupled to thepump housing; and a pressure sensing system, embedded in the proximalshell, wherein the pressure sensing system includes a pressure sensorand a pressure sensing chamber which is filled with an incompressiblefluid for pressure transmission. The driveline includes a pneumaticlumen, at least one electric wire and a tether, wherein the electricwires and the tether are disposed in the driveline wall. The feedthroughconnects the driveline to the pump housing.

An embodiment of the present displacement pump invention discloses apulsatile blood pump design that incorporates a non-stationary foldingline concept in the construct of a long-duration blood sac that maysubstantially prolong the durability of a displacement type blood pump.Also, a miniature pressure sensing system is disclosed, which can beused to serve as reference waveform for real-time pump control as wellas for long-term trending analysis, disease monitoring and diagnosis,based on evidence-based mega data. Further, the embedded pressuresensing system is non-blood contacting, which, hence, greatly improvesthe reliability requirements in building an implantable sensor system.

The embodiment of the present blood pump invention has at least one ofthe following advantages or effects. By the feedthrough connection ofthe driveline to the pump housing, a compact feedthrough design isprovided to make the electric wiring and signal transduction more robustand fault tolerant. Further, a compact feedthrough design integrates thesensory electric wires and the pneumatic tubing with the blood pump.This compactness attribute is particularly essential for implantdevices. It not only simplifies surgical operation and mitigatesperi-operative implantation risks, but also contributes to the reductionof post-operative morbidity associated with driveline infection.

In some blood pump embodiments, the feedthrough is integrated with adistal shell of the pump housing and the feedthrough has a first portionas an extension of the distal shell in which the pneumatic lumen, thetether and the electric wire of the driveline are coupled, and a secondportion being interlocked with the first portion working as a bendrelief of the driveline, to the advantage of anatomic adaptivity andfitness to the implant site geometry.

An embodiment of the present flow communication invention provides anaortic adapter assembly, for an implantable ventricular assist device,comprising: a T-shaped aortic adapter, including: an inserted conduitportion, an extruded neck portion, wherein the inserted conduit portionis joined with the extruded neck portion, both having a blood-contactingsurface which is smooth; and a truss, disposed in the inserted conduitportion; wherein the T-shaped aortic adapter has a polymeric elastomerreinforced by the truss having a Nitinol material; wherein the insertedconduit portion has a wall which is gradually thinning at two conduitends of the inserted conduit portion, with a proper distance of a tip ofthe conduit end to the outmost boundary of the truss, and the conduitend possesses a compliance-matching effect to an implant site artery;wherein a proximal end of the extruded neck portion is configured to bejoined with an inlet adapter of a blood pump.

The embodiment of the present flow communication invention has at leastone of the following advantages or effects. The present inventiondiscloses a flow communicator assembly that enables blood flow transportinto and out of a para-aortic ventricular assist device 10, inparticular, a counterpulsatile blood pump. Unlike many existing flowcommunicators that employ rough surface approach to promoteendothelialization so as to avert thrombotic adverse events to occur,the present aortic adapter invention adopts a smooth surface, insertiontype prosthetic graft concept to construct the flow communicator.Further, a compliance-matching design is embodied around the insertedconduit ends, which combines the gradually thinning wall characteristicwith a super-elastic Nitinol supported thin-walled polymer to accomplishthe endo-leak free requirement. Abnormal high pressure, high shear, andlow-speed recirculation flow phenomena associated with para-aorticcounterpulsatile pumping are contained within the artificial surface ofthe inserted conduit. Hence, the pathologic device-induced hemodynamicinfluences and risk factors are substantially eliminated and long-termvascular maladaptation related adverse events such as endothelial cellerosion, lipid infiltration, smooth muscle cell proliferation, vascularstenosis, arterial wall dissection, etc. are significantly reduced. Toaccomplish a sound connection of the semi-rigid flow adapter to a bloodpump, a quick connector type coupler is invented. This coupler has aself-alignment interface design that minimizes the step and gapdiscontinuity and hence reduces the possibility of thrombotic adverseevents to occur at interface joint. Accompanying this aortic adapterinvention is a specially designed delivery method that assures a quickand safe delivery procedure. The crimped aortic adapter is made into aprepack delivery configuration whose overall size is reduced into halfof its deployed configuration. This prepacked adapter can be insertedinto the implant site aorta easily and self-expands into its originaldeployed configuration, resulting in a snuggly fitted flow communicatorwithout the concern of endo-leak. It is not only beneficial for surgicaloperations that mitigate peri-operative implantation risks, but alsocontributes to the reduction of post-operative morbidity associated withdevice-induced flow and implant site vascular maladaptation.

Use of ordinal terms such as “first”, “second”, “third”, etc., in theclaims to modify a claim element does not by itself connote anypriority, precedence, or order of one claim element over another or thetemporal order in which acts of a method are performed, but are usedmerely as labels to distinguish one claim element having a certain namefrom another element having the same name (but for use of the ordinalterm) to distinguish the claim elements.

Embodiments of this invention are described, and variations of thoseembodiments may become apparent to those of ordinary skill in the artupon reading the foregoing description. Accordingly, this inventionincludes all modifications and equivalents of the subject matter recitedin the claims.

What is claimed is:
 1. A para-aortic blood pump device, comprising: ablood pump, comprising a pump housing, a blood sac, and a pressuresensor, the blood sac disposed in the pump housing, and the pressuresensor being installed in the pump housing for monitoring blood pressureinside the blood pump to generate an electrical blood pressure signal;an aortic adapter, being a T-manifold shaped conduit, coupled to theblood pump, and provided for integrating the blood pump with humanaorta; a driveline, coupled to the pump housing of the blood pump, fortransmitting the electrical blood pressure signal received from thepressure sensor; and a driver, coupled to the driveline for receivingthe electrical blood pressure signal, and comprising anelectro-mechanical actuator to generate a pressure pulse according tothe electrical blood pressure signal, and providing the pressure pulseto the blood pump through the driveline.
 2. The para-aortic blood pumpdevice according to claim 1, wherein the driver further comprises adriveline controller and a vibrator, and the driveline controller isused for processing the electrical blood pressure signal, and thevibrator is used for providing an audible alarm or a tactile feedback.3. The para-aortic blood pump device according to claim 1, wherein thedriveline and a part of the driver are substituted by a distaldriveline, a driveline interconnector and a proximal driveline, and thedistal driveline is provided for transmitting the electrical bloodpressure signal and the pressure pulse to the blood pump, and thedriveline interconnector comprises a driveline controller and avibrator, and the driveline controller is used for processing theelectrical blood pressure signal, and the vibrator is used for providingan audible alarm or a tactile feedback.
 4. The para-aortic blood pumpdevice according to claim 1, wherein the blood pump and the aorticadapter are integrally formed.
 5. The para-aortic blood pump deviceaccording to claim 1, further comprising a coupler, and the couplerincludes a coupling adapter installed at a neck of the aortic adapterfor coupling the blood pump to the aortic adapter.
 6. The para-aorticblood pump device according to claim 1, wherein two gradually flaredconduit ends of the aortic adapter constitute a smooth transition of anelastic property, being progressively softer in proportion to the wallthickness of the aortic adapter toward the conduit end.
 7. Thepara-aortic blood pump device according to claim 1, wherein the pumphousing of the blood pump is installed with the blood sac therein, andthe blood sac is an oval-shaped membrane body of revolution to acenterline of the blood pump, at two ends there are two polymeric stemsthat are bonded with the blood sac, working as a flexing/stretchingrelief mechanism to alleviate stress concentration when attached ontothe pump housing of the blood pump.
 8. The para-aortic blood pump deviceaccording to claim 1, wherein the pump housing of the blood pump has anopening, and the opening continuously integrates with the aortic adapterthat provides a smooth interface with a neck of the aortic adapter. 9.The para-aortic blood pump device according to claim 1, wherein theelectro-mechanical actuator comprises a pressure equalization valveconnected to a cylinder of the electro-mechanical actuator, and thepressure equalization valve is opened periodically so that an airpressure in the cylinder can be set to be in equilibrium withatmospheric pressure.
 10. The para-aortic blood pump device according toclaim 1, wherein the para-aortic blood pump device provides acounter-pulsatile augmentation of systemic blood flow during diastole(heart relaxation) to improve myocardial and organ perfusion whilereducing left ventricular workload during systole (heart contraction).11. The para-aortic blood pump device according to claim 1, wherein thedriver further comprises a trigger-detection micro controller unit, andthe electrical blood pressure signal provides the sensed pressurewaveform within the blood pump for the trigger-detection microcontroller unit to compute and determine the eject and fill timings forthe electro-mechanical actuator.
 12. The para-aortic blood pump deviceaccording to claim 1, wherein the electro-mechanical actuator comprisesa motor and a ball screw unit that drives a reciprocating piston withina cylinder of the electro-mechanical actuator; the movement of thepiston pushes and withdraws air via the driveline coupled to the bloodpump.
 13. The para-aortic blood pump device according to claim 1,wherein the electro-mechanical actuator is a pneumatic actuatorincludes: a brushless servo motor, a ball screw unit, a piston andcylinder assembly, wherein atmospheric air is used as a driving mediumto reciprocally eject and fill the blood pump; and a pressureequalization valve is equipped on the electro-mechanical actuator tosolve the problems of air leakage at a piston ring of the pistoncylinder assembly and condensation of vapor permeated out from a bloodsac.
 14. The para-aortic blood pump device according to claim 11,wherein the driver receives the electrical blood pressure signal andprocesses the electrical blood pressure signal using trigger detectionalgorithm to generate a trigger signal that commands a driver actuationin synchronization with the heart rhythm.
 15. The para-aortic blood pumpdevice according to claim 14, wherein, upon receiving the assignedtrigger timing, the micro controller unit sends commands to a motorcontroller to drive a piston of the electro-mechanical actuator, fromeject-to-fill or from fill-to-eject positions, to providecounter-pulsatile circulatory support including contraction unloadingduring the cardiac systolic phase and perfusion augmentation during thecardiac diastolic phase, respectively.
 16. The para-aortic blood pumpdevice according to claim 1, wherein the driver further comprises a userinterface, and the user interface comprises an indicator, an audioalarm, a button and a liquid crystal display (LCD).
 17. The para-aorticblood pump device according to claim 11, wherein, when the microcontroller unit loses the electrical blood pressure signal from theblood pump, a washout mode is launched automatically by the microcontroller unit to drive the electro-mechanical actuator, operating at apredetermined pumping rate and driver stroke volume.
 18. The para-aorticblood pump device according to claim 17, wherein the washout mode isused to prevent the formation of thrombus in the blood pump, which is adevice protection mode instead of providing circulatory support.
 19. Thepara-aortic blood pump device according to claim 7, wherein the bloodsac is anchored via a proximal stem to a proximal shell of the pumphousing and via a distal stem to a distal shell of the pump housing.